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In this article
NORM.INV is the reverse of NORM.DIST: give it a probability and it returns the value. Great for safety stock, and for simulations with RAND().
Syntax
=NORM.INV(probability, mean, standard_dev)| Argument | What it means |
|---|---|
probability |
Between 0 and 1. |
Examples
Example 1
=NORM.INV(0.95, 200, 30)Stock that covers demand on 95% of days (about 249).
Example 2
=NORM.INV(RAND(), 200, 30)One random simulated day of demand.
NORM.INV in practice
Where you will use it
- Value at a given percentile
- Safety stock levels
- Set targets at the 90th percentile
Worked example
| Probability | Formula | Result |
|---|---|---|
| 0.9 | =ROUND(NORM.INV(A2,50,10),2) | 62.82 |
| 0.5 | =ROUND(NORM.INV(A3,50,10),2) | 50 |
| 0.05 | =ROUND(NORM.INV(A4,50,10),2) | 33.55 |
Results calculated in Excel.
Mistakes people make
| Mistake | What to do instead |
|---|---|
| Probability outside 0-1 | #NUM! |
| Standard normal | Use NORM.S.INV for mean 0, SD 1 |
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📎 Practice files for this article
- 📗Practice workbook: Statistics advanced33 tasks on realistic sales data — type your formula, the Check column turns green when it is right. Answers sheet included.⬇ XLSX · 36 KB
Free to use for learning. Files with macros (.bas) are plain text — import them with Alt+F11 → File → Import File, and always test on a copy.
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