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NEGBINOMDIST Function

Excel 2007+

Summary

The NEGBINOMDIST function calculates the negative binomial distribution, giving the probability of experiencing a specific number of failures before achieving a fixed number of successes in independent trials with constant success probability. This legacy function models scenarios where successes are fixed and trials vary.

Syntax

NEGBINOMDIST(number_f, number_s, probability_s)

Parameters

Parameter	Type	Required	Description
number_f	`Number`	Yes	Number of failures (non-negative integer)
number_s	`Number`	Yes	Threshold number of successes (positive integer)
probability_s	`Number`	Yes	Probability of success per trial (0 to 1)

Using the NEGBINOMDIST Function

NEGBINOMDIST helps analyze processes where you need a certain number of successes, calculating how many failures might occur first. Use it for quality testing (defective items before good ones), marketing campaigns, or any repeated trial scenario with fixed success targets.

Common NEGBINOMDIST Examples

Quality Control Testing

=NEGBINOMDIST(10,5,0.25)

Probability of 10 defective items before finding 5 good ones (25% success rate). Returns approximately 0.0550.

Sales Target Probability

=NEGBINOMDIST(15,8,0.3)

Probability of 15 unsuccessful calls before 8 successful sales (30% close rate).

Dynamic Cell Reference

=NEGBINOMDIST(B2,C2,D2)

Uses cell values for flexible probability calculations.

Frequently Asked Questions

Use NEGBINOM.DIST(number_f, number_s, probability_s, FALSE) for identical results with better precision.

Negative binomial fixes successes and varies trials; binomial fixes trials and varies successes.

Arguments are truncated to integers automatically.

Common Errors and Solutions

#NUM!

Cause: number_f < 0, number_s < 1, probability_s < 0, or probability_s > 1

Solution: Verify all numeric constraints are met

#VALUE!

Cause: Non-numeric input provided

Solution: Ensure all arguments contain valid numbers

Notes

Legacy function - consider NEGBINOM.DIST for new workbooks
Truncates number_f and number_s to integers
Trials assumed independent with constant success probability
Excel 2007+ only

Compatibility

Available in: Excel 2007, Excel 2010, Excel 2013, Excel 2016, Excel 2019, Excel 2021, Microsoft 365

Not available in: Excel 2003 and earlier

Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+