In this article
GAMMAINV returns the value at a gamma probability. It is a compatibility function: Excel keeps it so workbooks from Excel 2007 and earlier still calculate, but Microsoft recommends GAMMA.INV for new work. Both give the same result.
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Syntax
=GAMMAINV(probability, alpha, beta)| Argument | What it means |
|---|---|
probability |
0..1 |
alpha, beta |
Shape, scale |
Examples
Example 1
=ROUND(GAMMAINV(A2,B2,C2),3)Result: 6.713. See the worked example table below for more cases.
💡 For new workbooks use GAMMA.INV: it gives the same answer and is the name Microsoft keeps documenting.
GAMMAINV in practice
Where you will use it
- Opening and checking older workbooks that use GAMMAINV
- Understanding formulas shared by colleagues on older Excel versions
- Knowing when to swap in GAMMA.INV for clarity
Worked example
| p | alpha | beta | Formula | Result |
|---|---|---|---|---|
| 0.5 | 2 | 4 | =ROUND(GAMMAINV(A2,B2,C2),3) | 6.713 |
| 0.95 | 2 | 4 | =ROUND(GAMMAINV(A3,B3,C3),3) | 18.975 |
| 0.9 | 3 | 5 | =ROUND(GAMMAINV(A4,B4,C4),3) | 26.612 |
Results calculated in Excel. Same result as GAMMA.INV.
Mistakes people make
| Mistake | What to do instead |
|---|---|
| Using GAMMAINV in new files | Prefer GAMMA.INV: 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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