In this article
NEGBINOMDIST returns the probability of a number of failures before the k-th success. It is a compatibility function: Excel keeps it so workbooks from Excel 2007 and earlier still calculate, but Microsoft recommends NEGBINOM.DIST for new work. Both give the same result.
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Syntax
=NEGBINOMDIST(number_f, number_s, probability_s)| Argument | What it means |
|---|---|
number_f |
Failures |
number_s |
Successes |
probability_s |
p |
Examples
Example 1
=ROUND(NEGBINOMDIST(A2,B2,C2),4)Result: 0.0567. See the worked example table below for more cases.
💡 For new workbooks use NEGBINOM.DIST: it gives the same answer and is the name Microsoft keeps documenting.
NEGBINOMDIST in practice
Where you will use it
- Opening and checking older workbooks that use NEGBINOMDIST
- Understanding formulas shared by colleagues on older Excel versions
- Knowing when to swap in NEGBINOM.DIST for clarity
Worked example
| Failures | Successes | p | Formula | Result |
|---|---|---|---|---|
| 10 | 3 | 0.2 | =ROUND(NEGBINOMDIST(A2,B2,C2),4) | 0.0567 |
| 5 | 3 | 0.2 | =ROUND(NEGBINOMDIST(A3,B3,C3),4) | 0.0551 |
| 20 | 2 | 0.1 | =ROUND(NEGBINOMDIST(A4,B4,C4),4) | 0.0255 |
Results calculated in Excel. Same result as NEGBINOM.DIST.
Mistakes people make
| Mistake | What to do instead |
|---|---|
| Using NEGBINOMDIST in new files | Prefer NEGBINOM.DIST: same result, clearer name, and the function Microsoft keeps improving |
| Mixing old and new names in one model | Pick one style per workbook so formulas are easy to audit |
Related functions
📚 Part of the free Excel course: Beginner → Expert · Try it in the Formula Lab or ask the AI Helper.
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