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Binomial Table: Exact and Cumulative Probabilities

A binomial table answers one question: if you run n independent trials that each succeed with probability p, how likely is a given number of successes k? Set the three inputs below and the matching cell lights up in the printable table, alongside the chance of exactly k, at most k and at least k. Every cell is checked against R's dbinom() and pbinom().

I want to find the chance of exactly k successes

The printed grid stops at n = 20 and p = 0.50, the way a textbook table does. The lookup itself has no such limit: any n up to 1000 and any p computes, and the tool tells you when your case has no printed cell.

n = 10 · p = 0.50

P(X = 7) = 0.1172

Exactly 7 successes in 10 trials.

P(X = k)
0.1172
P(X ≤ k)
0.9453
P(X ≥ k)
0.1719
mean np
5.00

Full binomial table, n = 1 to 20

Rows step through the number of trials n and the successes k; columns are the success probability p. The exact table gives P(X = k), the cumulative table gives P(X ≤ k). Both are plain HTML, so they print and copy, and your lookup above highlights the cell you want.

Exact binomial probability of k successes in n trials
nk.05.10.15.20.25.30.35.40.45.50
100.95000.90000.85000.80000.75000.70000.65000.60000.55000.5000
10.05000.10000.15000.20000.25000.30000.35000.40000.45000.5000
200.90250.81000.72250.64000.56250.49000.42250.36000.30250.2500
10.09500.18000.25500.32000.37500.42000.45500.48000.49500.5000
20.00250.01000.02250.04000.06250.09000.12250.16000.20250.2500
300.85740.72900.61410.51200.42190.34300.27460.21600.16640.1250
10.13540.24300.32510.38400.42190.44100.44360.43200.40840.3750
20.00710.02700.05740.09600.14060.18900.23890.28800.33410.3750
30.00010.00100.00340.00800.01560.02700.04290.06400.09110.1250
400.81450.65610.52200.40960.31640.24010.17850.12960.09150.0625
10.17150.29160.36850.40960.42190.41160.38450.34560.29950.2500
20.01350.04860.09750.15360.21090.26460.31050.34560.36750.3750
30.00050.00360.01150.02560.04690.07560.11150.15360.20050.2500
40.00000.00010.00050.00160.00390.00810.01500.02560.04100.0625
500.77380.59050.44370.32770.23730.16810.11600.07780.05030.0313
10.20360.32810.39150.40960.39550.36020.31240.25920.20590.1563
20.02140.07290.13820.20480.26370.30870.33640.34560.33690.3125
30.00110.00810.02440.05120.08790.13230.18110.23040.27570.3125
40.00000.00050.00220.00640.01460.02840.04880.07680.11280.1563
50.00000.00000.00010.00030.00100.00240.00530.01020.01850.0313
600.73510.53140.37710.26210.17800.11760.07540.04670.02770.0156
10.23210.35430.39930.39320.35600.30250.24370.18660.13590.0938
20.03050.09840.17620.24580.29660.32410.32800.31100.27800.2344
30.00210.01460.04150.08190.13180.18520.23550.27650.30320.3125
40.00010.00120.00550.01540.03300.05950.09510.13820.18610.2344
50.00000.00010.00040.00150.00440.01020.02050.03690.06090.0938
60.00000.00000.00000.00010.00020.00070.00180.00410.00830.0156
700.69830.47830.32060.20970.13350.08240.04900.02800.01520.0078
10.25730.37200.39600.36700.31150.24710.18480.13060.08720.0547
20.04060.12400.20970.27530.31150.31770.29850.26130.21400.1641
30.00360.02300.06170.11470.17300.22690.26790.29030.29180.2734
40.00020.00260.01090.02870.05770.09720.14420.19350.23880.2734
50.00000.00020.00120.00430.01150.02500.04660.07740.11720.1641
60.00000.00000.00010.00040.00130.00360.00840.01720.03200.0547
70.00000.00000.00000.00000.00010.00020.00060.00160.00370.0078
800.66340.43050.27250.16780.10010.05760.03190.01680.00840.0039
10.27930.38260.38470.33550.26700.19770.13730.08960.05480.0313
20.05150.14880.23760.29360.31150.29650.25870.20900.15690.1094
30.00540.03310.08390.14680.20760.25410.27860.27870.25680.2188
40.00040.00460.01850.04590.08650.13610.18750.23220.26270.2734
50.00000.00040.00260.00920.02310.04670.08080.12390.17190.2188
60.00000.00000.00020.00110.00380.01000.02170.04130.07030.1094
70.00000.00000.00000.00010.00040.00120.00330.00790.01640.0313
80.00000.00000.00000.00000.00000.00010.00020.00070.00170.0039
900.63020.38740.23160.13420.07510.04040.02070.01010.00460.0020
10.29850.38740.36790.30200.22530.15560.10040.06050.03390.0176
20.06290.17220.25970.30200.30030.26680.21620.16120.11100.0703
30.00770.04460.10690.17620.23360.26680.27160.25080.21190.1641
40.00060.00740.02830.06610.11680.17150.21940.25080.26000.2461
50.00000.00080.00500.01650.03890.07350.11810.16720.21280.2461
60.00000.00010.00060.00280.00870.02100.04240.07430.11600.1641
70.00000.00000.00000.00030.00120.00390.00980.02120.04070.0703
80.00000.00000.00000.00000.00010.00040.00130.00350.00830.0176
90.00000.00000.00000.00000.00000.00000.00010.00030.00080.0020
1000.59870.34870.19690.10740.05630.02820.01350.00600.00250.0010
10.31510.38740.34740.26840.18770.12110.07250.04030.02070.0098
20.07460.19370.27590.30200.28160.23350.17570.12090.07630.0439
30.01050.05740.12980.20130.25030.26680.25220.21500.16650.1172
40.00100.01120.04010.08810.14600.20010.23770.25080.23840.2051
50.00010.00150.00850.02640.05840.10290.15360.20070.23400.2461
60.00000.00010.00120.00550.01620.03680.06890.11150.15960.2051
70.00000.00000.00010.00080.00310.00900.02120.04250.07460.1172
80.00000.00000.00000.00010.00040.00140.00430.01060.02290.0439
90.00000.00000.00000.00000.00000.00010.00050.00160.00420.0098
100.00000.00000.00000.00000.00000.00000.00000.00010.00030.0010
1100.56880.31380.16730.08590.04220.01980.00880.00360.00140.0005
10.32930.38350.32480.23620.15490.09320.05180.02660.01250.0054
20.08670.21310.28660.29530.25810.19980.13950.08870.05130.0269
30.01370.07100.15170.22150.25810.25680.22540.17740.12590.0806
40.00140.01580.05360.11070.17210.22010.24280.23650.20600.1611
50.00010.00250.01320.03880.08030.13210.18300.22070.23600.2256
60.00000.00030.00230.00970.02680.05660.09850.14710.19310.2256
70.00000.00000.00030.00170.00640.01730.03790.07010.11280.1611
80.00000.00000.00000.00020.00110.00370.01020.02340.04620.0806
90.00000.00000.00000.00000.00010.00050.00180.00520.01260.0269
100.00000.00000.00000.00000.00000.00000.00020.00070.00210.0054
110.00000.00000.00000.00000.00000.00000.00000.00000.00020.0005
1200.54040.28240.14220.06870.03170.01380.00570.00220.00080.0002
10.34130.37660.30120.20620.12670.07120.03680.01740.00750.0029
20.09880.23010.29240.28350.23230.16780.10880.06390.03390.0161
30.01730.08520.17200.23620.25810.23970.19540.14190.09230.0537
40.00210.02130.06830.13290.19360.23110.23670.21280.17000.1208
50.00020.00380.01930.05320.10320.15850.20390.22700.22250.1934
60.00000.00050.00400.01550.04010.07920.12810.17660.21240.2256
70.00000.00000.00060.00330.01150.02910.05910.10090.14890.1934
80.00000.00000.00010.00050.00240.00780.01990.04200.07620.1208
90.00000.00000.00000.00010.00040.00150.00480.01250.02770.0537
100.00000.00000.00000.00000.00000.00020.00080.00250.00680.0161
110.00000.00000.00000.00000.00000.00000.00010.00030.00100.0029
120.00000.00000.00000.00000.00000.00000.00000.00000.00010.0002
1300.51330.25420.12090.05500.02380.00970.00370.00130.00040.0001
10.35120.36720.27740.17870.10290.05400.02590.01130.00450.0016
20.11090.24480.29370.26800.20590.13880.08360.04530.02200.0095
30.02140.09970.19000.24570.25170.21810.16510.11070.06600.0349
40.00280.02770.08380.15350.20970.23370.22220.18450.13500.0873
50.00030.00550.02660.06910.12580.18030.21540.22140.19890.1571
60.00000.00080.00630.02300.05590.10300.15460.19680.21690.2095
70.00000.00010.00110.00580.01860.04420.08330.13120.17750.2095
80.00000.00000.00010.00110.00470.01420.03360.06560.10890.1571
90.00000.00000.00000.00010.00090.00340.01010.02430.04950.0873
100.00000.00000.00000.00000.00010.00060.00220.00650.01620.0349
110.00000.00000.00000.00000.00000.00010.00030.00120.00360.0095
120.00000.00000.00000.00000.00000.00000.00000.00010.00050.0016
130.00000.00000.00000.00000.00000.00000.00000.00000.00000.0001
1400.48770.22880.10280.04400.01780.00680.00240.00080.00020.0001
10.35930.35590.25390.15390.08320.04070.01810.00730.00270.0009
20.12290.25700.29120.25010.18020.11340.06340.03170.01410.0056
30.02590.11420.20560.25010.24020.19430.13660.08450.04620.0222
40.00370.03490.09980.17200.22020.22900.20220.15490.10400.0611
50.00040.00780.03520.08600.14680.19630.21780.20660.17010.1222
60.00000.00130.00930.03220.07340.12620.17590.20660.20880.1833
70.00000.00020.00190.00920.02800.06180.10820.15740.19520.2095
80.00000.00000.00030.00200.00820.02320.05100.09180.13980.1833
90.00000.00000.00000.00030.00180.00660.01830.04080.07620.1222
100.00000.00000.00000.00000.00030.00140.00490.01360.03120.0611
110.00000.00000.00000.00000.00000.00020.00100.00330.00930.0222
120.00000.00000.00000.00000.00000.00000.00010.00050.00190.0056
130.00000.00000.00000.00000.00000.00000.00000.00010.00020.0009
140.00000.00000.00000.00000.00000.00000.00000.00000.00000.0001
1500.46330.20590.08740.03520.01340.00470.00160.00050.00010.0000
10.36580.34320.23120.13190.06680.03050.01260.00470.00160.0005
20.13480.26690.28560.23090.15590.09160.04760.02190.00900.0032
30.03070.12850.21840.25010.22520.17000.11100.06340.03180.0139
40.00490.04280.11560.18760.22520.21860.17920.12680.07800.0417
50.00060.01050.04490.10320.16510.20610.21230.18590.14040.0916
60.00000.00190.01320.04300.09170.14720.19060.20660.19140.1527
70.00000.00030.00300.01380.03930.08110.13190.17710.20130.1964
80.00000.00000.00050.00350.01310.03480.07100.11810.16470.1964
90.00000.00000.00010.00070.00340.01160.02980.06120.10480.1527
100.00000.00000.00000.00010.00070.00300.00960.02450.05150.0916
110.00000.00000.00000.00000.00010.00060.00240.00740.01910.0417
120.00000.00000.00000.00000.00000.00010.00040.00160.00520.0139
130.00000.00000.00000.00000.00000.00000.00010.00030.00100.0032
140.00000.00000.00000.00000.00000.00000.00000.00000.00010.0005
150.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000
1600.44010.18530.07430.02810.01000.00330.00100.00030.00010.0000
10.37060.32940.20970.11260.05350.02280.00870.00300.00090.0002
20.14630.27450.27750.21110.13360.07320.03530.01500.00560.0018
30.03590.14230.22850.24630.20790.14650.08880.04680.02150.0085
40.00610.05140.13110.20010.22520.20400.15530.10140.05720.0278
50.00080.01370.05550.12010.18020.20990.20080.16230.11230.0667
60.00010.00280.01800.05500.11010.16490.19820.19830.16840.1222
70.00000.00040.00450.01970.05240.10100.15240.18890.19690.1746
80.00000.00010.00090.00550.01970.04870.09230.14170.18120.1964
90.00000.00000.00010.00120.00580.01850.04420.08400.13180.1746
100.00000.00000.00000.00020.00140.00560.01670.03920.07550.1222
110.00000.00000.00000.00000.00020.00130.00490.01420.03370.0667
120.00000.00000.00000.00000.00000.00020.00110.00400.01150.0278
130.00000.00000.00000.00000.00000.00000.00020.00080.00290.0085
140.00000.00000.00000.00000.00000.00000.00000.00010.00050.0018
150.00000.00000.00000.00000.00000.00000.00000.00000.00010.0002
160.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000
1700.41810.16680.06310.02250.00750.00230.00070.00020.00000.0000
10.37410.31500.18930.09570.04260.01690.00600.00190.00050.0001
20.15750.28000.26730.19140.11360.05810.02600.01020.00350.0010
30.04150.15560.23590.23930.18930.12450.07010.03410.01440.0052
40.00760.06050.14570.20930.22090.18680.13200.07960.04110.0182
50.00100.01750.06680.13610.19140.20810.18490.13790.08750.0472
60.00010.00390.02360.06800.12760.17840.19910.18390.14320.0944
70.00000.00070.00650.02670.06680.12010.16850.19270.18410.1484
80.00000.00010.00140.00840.02790.06440.11340.16060.18830.1855
90.00000.00000.00030.00210.00930.02760.06110.10700.15400.1855
100.00000.00000.00000.00040.00250.00950.02630.05710.10080.1484
110.00000.00000.00000.00010.00050.00260.00900.02420.05250.0944
120.00000.00000.00000.00000.00010.00060.00240.00810.02150.0472
130.00000.00000.00000.00000.00000.00010.00050.00210.00680.0182
140.00000.00000.00000.00000.00000.00000.00010.00040.00160.0052
150.00000.00000.00000.00000.00000.00000.00000.00010.00030.0010
160.00000.00000.00000.00000.00000.00000.00000.00000.00000.0001
170.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000
1800.39720.15010.05360.01800.00560.00160.00040.00010.00000.0000
10.37630.30020.17040.08110.03380.01260.00420.00120.00030.0001
20.16830.28350.25560.17230.09580.04580.01900.00690.00220.0006
30.04730.16800.24060.22970.17040.10460.05470.02460.00950.0031
40.00930.07000.15920.21530.21300.16810.11040.06140.02910.0117
50.00140.02180.07870.15070.19880.20170.16640.11460.06660.0327
60.00020.00520.03010.08160.14360.18730.19410.16550.11810.0708
70.00000.00100.00910.03500.08200.13760.17920.18920.16570.1214
80.00000.00020.00220.01200.03760.08110.13270.17340.18640.1669
90.00000.00000.00040.00330.01390.03860.07940.12840.16940.1855
100.00000.00000.00010.00080.00420.01490.03850.07710.12480.1669
110.00000.00000.00000.00010.00100.00460.01510.03740.07420.1214
120.00000.00000.00000.00000.00020.00120.00470.01450.03540.0708
130.00000.00000.00000.00000.00000.00020.00120.00450.01340.0327
140.00000.00000.00000.00000.00000.00000.00020.00110.00390.0117
150.00000.00000.00000.00000.00000.00000.00000.00020.00090.0031
160.00000.00000.00000.00000.00000.00000.00000.00000.00010.0006
170.00000.00000.00000.00000.00000.00000.00000.00000.00000.0001
180.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000
1900.37740.13510.04560.01440.00420.00110.00030.00010.00000.0000
10.37740.28520.15290.06850.02680.00930.00290.00080.00020.0000
20.17870.28520.24280.15400.08030.03580.01380.00460.00130.0003
30.05330.17960.24280.21820.15170.08690.04220.01750.00620.0018
40.01120.07980.17140.21820.20230.14910.09090.04670.02030.0074
50.00180.02660.09070.16360.20230.19160.14680.09330.04970.0222
60.00020.00690.03740.09550.15740.19160.18440.14510.09490.0518
70.00000.00140.01220.04430.09740.15250.18440.17970.14430.0961
80.00000.00020.00320.01660.04870.09810.14890.17970.17710.1442
90.00000.00000.00070.00510.01980.05140.09800.14640.17710.1762
100.00000.00000.00010.00130.00660.02200.05280.09760.14490.1762
110.00000.00000.00000.00030.00180.00770.02330.05320.09700.1442
120.00000.00000.00000.00000.00040.00220.00830.02370.05290.0961
130.00000.00000.00000.00000.00010.00050.00240.00850.02330.0518
140.00000.00000.00000.00000.00000.00010.00060.00240.00820.0222
150.00000.00000.00000.00000.00000.00000.00010.00050.00220.0074
160.00000.00000.00000.00000.00000.00000.00000.00010.00050.0018
170.00000.00000.00000.00000.00000.00000.00000.00000.00010.0003
180.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000
190.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000
2000.35850.12160.03880.01150.00320.00080.00020.00000.00000.0000
10.37740.27020.13680.05760.02110.00680.00200.00050.00010.0000
20.18870.28520.22930.13690.06690.02780.01000.00310.00080.0002
30.05960.19010.24280.20540.13390.07160.03230.01230.00400.0011
40.01330.08980.18210.21820.18970.13040.07380.03500.01390.0046
50.00220.03190.10280.17460.20230.17890.12720.07460.03650.0148
60.00030.00890.04540.10910.16860.19160.17120.12440.07460.0370
70.00000.00200.01600.05450.11240.16430.18440.16590.12210.0739
80.00000.00040.00460.02220.06090.11440.16140.17970.16230.1201
90.00000.00010.00110.00740.02710.06540.11580.15970.17710.1602
100.00000.00000.00020.00200.00990.03080.06860.11710.15930.1762
110.00000.00000.00000.00050.00300.01200.03360.07100.11850.1602
120.00000.00000.00000.00010.00080.00390.01360.03550.07270.1201
130.00000.00000.00000.00000.00020.00100.00450.01460.03660.0739
140.00000.00000.00000.00000.00000.00020.00120.00490.01500.0370
150.00000.00000.00000.00000.00000.00000.00030.00130.00490.0148
160.00000.00000.00000.00000.00000.00000.00000.00030.00130.0046
170.00000.00000.00000.00000.00000.00000.00000.00000.00020.0011
180.00000.00000.00000.00000.00000.00000.00000.00000.00000.0002
190.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000
200.00000.00000.00000.00000.00000.00000.00000.00000.00000.0000
Cumulative binomial probability of at most k successes in n trials
nk.05.10.15.20.25.30.35.40.45.50
100.95000.90000.85000.80000.75000.70000.65000.60000.55000.5000
11.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
200.90250.81000.72250.64000.56250.49000.42250.36000.30250.2500
10.99750.99000.97750.96000.93750.91000.87750.84000.79750.7500
21.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
300.85740.72900.61410.51200.42190.34300.27460.21600.16640.1250
10.99280.97200.93930.89600.84380.78400.71830.64800.57480.5000
20.99990.99900.99660.99200.98440.97300.95710.93600.90890.8750
31.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
400.81450.65610.52200.40960.31640.24010.17850.12960.09150.0625
10.98600.94770.89050.81920.73830.65170.56300.47520.39100.3125
20.99950.99630.98800.97280.94920.91630.87350.82080.75850.6875
31.00000.99990.99950.99840.99610.99190.98500.97440.95900.9375
41.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
500.77380.59050.44370.32770.23730.16810.11600.07780.05030.0313
10.97740.91850.83520.73730.63280.52820.42840.33700.25620.1875
20.99880.99140.97340.94210.89650.83690.76480.68260.59310.5000
31.00000.99950.99780.99330.98440.96920.94600.91300.86880.8125
41.00001.00000.99990.99970.99900.99760.99470.98980.98150.9688
51.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
600.73510.53140.37710.26210.17800.11760.07540.04670.02770.0156
10.96720.88570.77650.65540.53390.42020.31910.23330.16360.1094
20.99780.98420.95270.90110.83060.74430.64710.54430.44150.3438
30.99990.99870.99410.98300.96240.92950.88260.82080.74470.6563
41.00000.99990.99960.99840.99540.98910.97770.95900.93080.8906
51.00001.00001.00000.99990.99980.99930.99820.99590.99170.9844
61.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
700.69830.47830.32060.20970.13350.08240.04900.02800.01520.0078
10.95560.85030.71660.57670.44490.32940.23380.15860.10240.0625
20.99620.97430.92620.85200.75640.64710.53230.41990.31640.2266
30.99980.99730.98790.96670.92940.87400.80020.71020.60830.5000
41.00000.99980.99880.99530.98710.97120.94440.90370.84710.7734
51.00001.00000.99990.99960.99870.99620.99100.98120.96430.9375
61.00001.00001.00001.00000.99990.99980.99940.99840.99630.9922
71.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
800.66340.43050.27250.16780.10010.05760.03190.01680.00840.0039
10.94280.81310.65720.50330.36710.25530.16910.10640.06320.0352
20.99420.96190.89480.79690.67850.55180.42780.31540.22010.1445
30.99960.99500.97860.94370.88620.80590.70640.59410.47700.3633
41.00000.99960.99710.98960.97270.94200.89390.82630.73960.6367
51.00001.00000.99980.99880.99580.98870.97470.95020.91150.8555
61.00001.00001.00000.99990.99960.99870.99640.99150.98190.9648
71.00001.00001.00001.00001.00000.99990.99980.99930.99830.9961
81.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
900.63020.38740.23160.13420.07510.04040.02070.01010.00460.0020
10.92880.77480.59950.43620.30030.19600.12110.07050.03850.0195
20.99160.94700.85910.73820.60070.46280.33730.23180.14950.0898
30.99940.99170.96610.91440.83430.72970.60890.48260.36140.2539
41.00000.99910.99440.98040.95110.90120.82830.73340.62140.5000
51.00000.99990.99940.99690.99000.97470.94640.90060.83420.7461
61.00001.00001.00000.99970.99870.99570.98880.97500.95020.9102
71.00001.00001.00001.00000.99990.99960.99860.99620.99090.9805
81.00001.00001.00001.00001.00001.00000.99990.99970.99920.9980
91.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1000.59870.34870.19690.10740.05630.02820.01350.00600.00250.0010
10.91390.73610.54430.37580.24400.14930.08600.04640.02330.0107
20.98850.92980.82020.67780.52560.38280.26160.16730.09960.0547
30.99900.98720.95000.87910.77590.64960.51380.38230.26600.1719
40.99990.99840.99010.96720.92190.84970.75150.63310.50440.3770
51.00000.99990.99860.99360.98030.95270.90510.83380.73840.6230
61.00001.00000.99990.99910.99650.98940.97400.94520.89800.8281
71.00001.00001.00000.99990.99960.99840.99520.98770.97260.9453
81.00001.00001.00001.00001.00000.99990.99950.99830.99550.9893
91.00001.00001.00001.00001.00001.00001.00000.99990.99970.9990
101.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1100.56880.31380.16730.08590.04220.01980.00880.00360.00140.0005
10.89810.69740.49220.32210.19710.11300.06060.03020.01390.0059
20.98480.91040.77880.61740.45520.31270.20010.11890.06520.0327
30.99840.98150.93060.83890.71330.56960.42560.29630.19110.1133
40.99990.99720.98410.94960.88540.78970.66830.53280.39710.2744
51.00000.99970.99730.98830.96570.92180.85130.75350.63310.5000
61.00001.00000.99970.99800.99240.97840.94990.90060.82620.7256
71.00001.00001.00000.99980.99880.99570.98780.97070.93900.8867
81.00001.00001.00001.00000.99990.99940.99800.99410.98520.9673
91.00001.00001.00001.00001.00001.00000.99980.99930.99780.9941
101.00001.00001.00001.00001.00001.00001.00001.00000.99980.9995
111.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1200.54040.28240.14220.06870.03170.01380.00570.00220.00080.0002
10.88160.65900.44350.27490.15840.08500.04240.01960.00830.0032
20.98040.88910.73580.55830.39070.25280.15130.08340.04210.0193
30.99780.97440.90780.79460.64880.49250.34670.22530.13450.0730
40.99980.99570.97610.92740.84240.72370.58330.43820.30440.1938
51.00000.99950.99540.98060.94560.88220.78730.66520.52690.3872
61.00000.99990.99930.99610.98570.96140.91540.84180.73930.6128
71.00001.00000.99990.99940.99720.99050.97450.94270.88830.8062
81.00001.00001.00000.99990.99960.99830.99440.98470.96440.9270
91.00001.00001.00001.00001.00000.99980.99920.99720.99210.9807
101.00001.00001.00001.00001.00001.00000.99990.99970.99890.9968
111.00001.00001.00001.00001.00001.00001.00001.00000.99990.9998
121.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1300.51330.25420.12090.05500.02380.00970.00370.00130.00040.0001
10.86460.62130.39830.23360.12670.06370.02960.01260.00490.0017
20.97550.86610.69200.50170.33260.20250.11320.05790.02690.0112
30.99690.96580.88200.74730.58430.42060.27830.16860.09290.0461
40.99970.99350.96580.90090.79400.65430.50050.35300.22790.1334
51.00000.99910.99250.97000.91980.83460.71590.57440.42680.2905
61.00000.99990.99870.99300.97570.93760.87050.77120.64370.5000
71.00001.00000.99980.99880.99440.98180.95380.90230.82120.7095
81.00001.00001.00000.99980.99900.99600.98740.96790.93020.8666
91.00001.00001.00001.00000.99990.99930.99750.99220.97970.9539
101.00001.00001.00001.00001.00000.99990.99970.99870.99590.9888
111.00001.00001.00001.00001.00001.00001.00000.99990.99950.9983
121.00001.00001.00001.00001.00001.00001.00001.00001.00000.9999
131.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1400.48770.22880.10280.04400.01780.00680.00240.00080.00020.0001
10.84700.58460.35670.19790.10100.04750.02050.00810.00290.0009
20.96990.84160.64790.44810.28110.16080.08390.03980.01700.0065
30.99580.95590.85350.69820.52130.35520.22050.12430.06320.0287
40.99960.99080.95330.87020.74150.58420.42270.27930.16720.0898
51.00000.99850.98850.95610.88830.78050.64050.48590.33730.2120
61.00000.99980.99780.98840.96170.90670.81640.69250.54610.3953
71.00001.00000.99970.99760.98970.96850.92470.84990.74140.6047
81.00001.00001.00000.99960.99780.99170.97570.94170.88110.7880
91.00001.00001.00001.00000.99970.99830.99400.98250.95740.9102
101.00001.00001.00001.00001.00000.99980.99890.99610.98860.9713
111.00001.00001.00001.00001.00001.00000.99990.99940.99780.9935
121.00001.00001.00001.00001.00001.00001.00000.99990.99970.9991
131.00001.00001.00001.00001.00001.00001.00001.00001.00000.9999
141.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1500.46330.20590.08740.03520.01340.00470.00160.00050.00010.0000
10.82900.54900.31860.16710.08020.03530.01420.00520.00170.0005
20.96380.81590.60420.39800.23610.12680.06170.02710.01070.0037
30.99450.94440.82270.64820.46130.29690.17270.09050.04240.0176
40.99940.98730.93830.83580.68650.51550.35190.21730.12040.0592
50.99990.99780.98320.93890.85160.72160.56430.40320.26080.1509
61.00000.99970.99640.98190.94340.86890.75480.60980.45220.3036
71.00001.00000.99940.99580.98270.95000.88680.78690.65350.5000
81.00001.00000.99990.99920.99580.98480.95780.90500.81820.6964
91.00001.00001.00000.99990.99920.99630.98760.96620.92310.8491
101.00001.00001.00001.00000.99990.99930.99720.99070.97450.9408
111.00001.00001.00001.00001.00000.99990.99950.99810.99370.9824
121.00001.00001.00001.00001.00001.00000.99990.99970.99890.9963
131.00001.00001.00001.00001.00001.00001.00001.00000.99990.9995
141.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
151.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1600.44010.18530.07430.02810.01000.00330.00100.00030.00010.0000
10.81080.51470.28390.14070.06350.02610.00980.00330.00100.0003
20.95710.78920.56140.35180.19710.09940.04510.01830.00660.0021
30.99300.93160.78990.59810.40500.24590.13390.06510.02810.0106
40.99910.98300.92090.79820.63020.44990.28920.16660.08530.0384
50.99990.99670.97650.91830.81030.65980.49000.32880.19760.1051
61.00000.99950.99440.97330.92040.82470.68810.52720.36600.2272
71.00000.99990.99890.99300.97290.92560.84060.71610.56290.4018
81.00001.00000.99980.99850.99250.97430.93290.85770.74410.5982
91.00001.00001.00000.99980.99840.99290.97710.94170.87590.7728
101.00001.00001.00001.00000.99970.99840.99380.98090.95140.8949
111.00001.00001.00001.00001.00000.99970.99870.99510.98510.9616
121.00001.00001.00001.00001.00001.00000.99980.99910.99650.9894
131.00001.00001.00001.00001.00001.00001.00000.99990.99940.9979
141.00001.00001.00001.00001.00001.00001.00001.00000.99990.9997
151.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
161.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1700.41810.16680.06310.02250.00750.00230.00070.00020.00000.0000
10.79220.48180.25250.11820.05010.01930.00670.00210.00060.0001
20.94970.76180.51980.30960.16370.07740.03270.01230.00410.0012
30.99120.91740.75560.54890.35300.20190.10280.04640.01840.0064
40.99880.97790.90130.75820.57390.38870.23480.12600.05960.0245
50.99990.99530.96810.89430.76530.59680.41970.26390.14710.0717
61.00000.99920.99170.96230.89290.77520.61880.44780.29020.1662
71.00000.99990.99830.98910.95980.89540.78720.64050.47430.3145
81.00001.00000.99970.99740.98760.95970.90060.80110.66260.5000
91.00001.00001.00000.99950.99690.98730.96170.90810.81660.6855
101.00001.00001.00000.99990.99940.99680.98800.96520.91740.8338
111.00001.00001.00001.00000.99990.99930.99700.98940.96990.9283
121.00001.00001.00001.00001.00000.99990.99940.99750.99140.9755
131.00001.00001.00001.00001.00001.00000.99990.99950.99810.9936
141.00001.00001.00001.00001.00001.00001.00000.99990.99970.9988
151.00001.00001.00001.00001.00001.00001.00001.00001.00000.9999
161.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
171.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1800.39720.15010.05360.01800.00560.00160.00040.00010.00000.0000
10.77350.45030.22410.09910.03950.01420.00460.00130.00030.0001
20.94190.73380.47970.27130.13530.06000.02360.00820.00250.0007
30.98910.90180.72020.50100.30570.16460.07830.03280.01200.0038
40.99850.97180.87940.71640.51870.33270.18860.09420.04110.0154
50.99980.99360.95810.86710.71750.53440.35500.20880.10770.0481
61.00000.99880.98820.94870.86100.72170.54910.37430.22580.1189
71.00000.99980.99730.98370.94310.85930.72830.56340.39150.2403
81.00001.00000.99950.99570.98070.94040.86090.73680.57780.4073
91.00001.00000.99990.99910.99460.97900.94030.86530.74730.5927
101.00001.00001.00000.99980.99880.99390.97880.94240.87200.7597
111.00001.00001.00001.00000.99980.99860.99380.97970.94630.8811
121.00001.00001.00001.00001.00000.99970.99860.99420.98170.9519
131.00001.00001.00001.00001.00001.00000.99970.99870.99510.9846
141.00001.00001.00001.00001.00001.00001.00000.99980.99900.9962
151.00001.00001.00001.00001.00001.00001.00001.00000.99990.9993
161.00001.00001.00001.00001.00001.00001.00001.00001.00000.9999
171.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
181.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
1900.37740.13510.04560.01440.00420.00110.00030.00010.00000.0000
10.75470.42030.19850.08290.03100.01040.00310.00080.00020.0000
20.93350.70540.44130.23690.11130.04620.01700.00550.00150.0004
30.98680.88500.68410.45510.26310.13320.05910.02300.00770.0022
40.99800.96480.85560.67330.46540.28220.15000.06960.02800.0096
50.99980.99140.94630.83690.66780.47390.29680.16290.07770.0318
61.00000.99830.98370.93240.82510.66550.48120.30810.17270.0835
71.00000.99970.99590.97670.92250.81800.66560.48780.31690.1796
81.00001.00000.99920.99330.97130.91610.81450.66750.49400.3238
91.00001.00000.99990.99840.99110.96740.91250.81390.67100.5000
101.00001.00001.00000.99970.99770.98950.96530.91150.81590.6762
111.00001.00001.00001.00000.99950.99720.98860.96480.91290.8204
121.00001.00001.00001.00000.99990.99940.99690.98840.96580.9165
131.00001.00001.00001.00001.00000.99990.99930.99690.98910.9682
141.00001.00001.00001.00001.00001.00000.99990.99940.99720.9904
151.00001.00001.00001.00001.00001.00001.00000.99990.99950.9978
161.00001.00001.00001.00001.00001.00001.00001.00000.99990.9996
171.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
181.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
191.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
2000.35850.12160.03880.01150.00320.00080.00020.00000.00000.0000
10.73580.39170.17560.06920.02430.00760.00210.00050.00010.0000
20.92450.67690.40490.20610.09130.03550.01210.00360.00090.0002
30.98410.86700.64770.41140.22520.10710.04440.01600.00490.0013
40.99740.95680.82980.62960.41480.23750.11820.05100.01890.0059
50.99970.98870.93270.80420.61720.41640.24540.12560.05530.0207
61.00000.99760.97810.91330.78580.60800.41660.25000.12990.0577
71.00000.99960.99410.96790.89820.77230.60100.41590.25200.1316
81.00000.99990.99870.99000.95910.88670.76240.59560.41430.2517
91.00001.00000.99980.99740.98610.95200.87820.75530.59140.4119
101.00001.00001.00000.99940.99610.98290.94680.87250.75070.5881
111.00001.00001.00000.99990.99910.99490.98040.94350.86920.7483
121.00001.00001.00001.00000.99980.99870.99400.97900.94200.8684
131.00001.00001.00001.00001.00000.99970.99850.99350.97860.9423
141.00001.00001.00001.00001.00001.00000.99970.99840.99360.9793
151.00001.00001.00001.00001.00001.00001.00000.99970.99850.9941
161.00001.00001.00001.00001.00001.00001.00001.00000.99970.9987
171.00001.00001.00001.00001.00001.00001.00001.00001.00000.9998
181.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
191.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
201.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000

A cell reading 0.0000 is not impossible, only smaller than 0.00005. The lookup above reports those small values in full instead of rounding them away. Cells are computed as exact fractions and rounded to four decimals, so each one is the true probability rather than a rounded decimal of a rounded decimal.

How this probability is computed
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The same thing in R

  

No data leaves your browser Verified against R's dbinom() and pbinom() Free, no sign-up

How to read this table

Say a treatment works 30% of the time and you give it to 15 patients. What is the chance it works for exactly 4 of them?

  1. Fix n, the number of trials. Fifteen patients, so find the block where n = 15. Each block runs from k = 0 down to k = n, and the number of trials never changes inside it.
  2. Find the row for k, the count you care about. You want exactly 4 successes, so take the row k = 4 inside that block.
  3. Find the column for p, the per-trial success probability. The treatment works 30% of the time, so use the p = .30 column. p is the chance for a single trial, never the chance for the whole run.
  4. Read the cell. Row and column meet at 0.2186, so there is roughly a 22% chance of exactly 4 successes out of 15.
  5. Need "4 or fewer" instead? Switch to the cumulative table and read the same spot: 0.5155. That is P(X ≤ 4), the sum of the k = 0, 1, 2, 3 and 4 rows.
  6. Need "at least 4"? There is no at-least table, because you do not need one. At least 4 is everything except 3 or fewer: 1 - 0.2969 = 0.7031, taking 0.2969 from the cumulative row k = 3.

When p is bigger than 0.5, count failures

Every printed binomial table stops at p = 0.50. That is not laziness: the right half would be the left half in a mirror, so it is left out and you flip the question instead.

A trial that succeeds with probability p fails with probability 1 - p. So counting k successes among n trials is the same as counting n - k failures, and the identity that follows lets one half of the table serve both:

P(X = k | n, p) = P(X = n - k | n, 1 - p) Suppose a shot lands 70% of the time and you take 10 of them. The chance of exactly 7 hits has no column, because there is no p = .70. But 7 hits out of 10 is the same event as 3 misses out of 10, and a miss has probability 0.30. So look up n = 10, k = 3, p = .30 and read 0.2668. Set p to 0.70 in the lookup above and the tool highlights that mirrored cell for you. P(X ≤ k | n, p) = P(X ≥ n - k | n, 1 - p) The cumulative version flips direction as well as side: at most k successes means at least n - k failures. Reading it off the cumulative table takes one subtraction, which the lookup shows you as it does it.

Which table, and when the binomial is the wrong model

You wantTableHow to read itR
Exactly k successesExactCell at row k, column pdbinom(k, n, p)
At most k (k or fewer)CumulativeCell at row k, column ppbinom(k, n, p)
At least k (k or more)Cumulative1 minus the cell at row k - 1pbinom(k - 1, n, p, lower.tail = FALSE)
Between a and bCumulativeCell at row b minus cell at row a - 1diff(pbinom(c(a - 1, b), n, p))

All of it assumes the binomial setup: a fixed number of trials, two outcomes per trial, the same p every time, and trials that do not influence each other. Sampling people without replacement from a small group breaks the last two (that is the hypergeometric); counting events in a window rather than successes in a fixed n means you want the Poisson instead.

Binomial table questions

How do I read a binomial table?

Find the block for your number of trials n, then the row for the successes k, then the column for the per-trial probability p. The cell where they meet is your answer: P(X = k) in the exact table, P(X ≤ k) in the cumulative one. The walkthrough above works a full example end to end.

What if my p is bigger than 0.5?

Count failures instead of successes. Because P(X = k | n, p) = P(X = n - k | n, 1 - p), a run with p = 0.7 is a run with p = 0.3 seen from the other side, so the table's left half covers both. For n = 10, p = 0.7, k = 7, look up n = 10, p = .30, k = 3. Enter p = 0.7 above and the tool highlights that mirrored cell and shows the flip.

What is the difference between the exact and cumulative tables?

Exact gives P(X = k), one bar of the distribution: the chance of precisely k successes. Cumulative gives P(X ≤ k), every bar from 0 up to k added together. "Exactly 7 heads" is exact; "no more than 7 heads" is cumulative; "at least 7 heads" is 1 minus the cumulative value at k = 6.

Why does my cell say 0.0000?

Because the probability is below 0.00005, not because it cannot happen. Twenty trials at p = .05 give exactly 20 successes with probability about 1e-26: real, just far too small for four decimals. The lookup above prints small values in full precision rather than rounding them to nothing.

What if my n is bigger than 20, or p is not a multiple of .05?

Then no printed table has your cell, and that is the limitation of printed tables rather than of the binomial. The lookup handles any n up to 1000 and any p, and says so when your case is off the grid. For heavier work use the binomial probability calculator, which adds ranges and inverse lookups.

Does this binomial table match R?

Yes. All 4600 printed cells and the lookup are checked against R's dbinom() and pbinom(), along with the edges (k = 0, k = n, tiny p, n up to 1000). The cells are computed as exact fractions rather than decimals, so each is the true probability rounded to four places.

Keep going