In this article
BETA.DIST gives the beta distribution, used for proportions and task-duration estimates (PERT). With A and B you can rescale it to any range, e.g. a project that takes 8 to 20 days.
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Syntax
=BETA.DIST(x, alpha, beta, cumulative, [A], [B])| Argument | What it means |
|---|---|
x |
Value |
alpha, beta |
Shape parameters |
cumulative |
TRUE = probability up to x |
A, B |
Optional lower and upper bounds (default 0 and 1) |
Examples
Example 1
=ROUND(BETA.DIST(A2,B2,C2,TRUE,D2,E2),4)Result: 0.4074. See the worked example table below for more cases.
BETA.DIST in practice
Where you will use it
- Chance a task finishes within N days in PERT estimates
- Modelling conversion rates or defect proportions
- Risk analysis with bounded outcomes
Worked example
| x | alpha | beta | A | B | Formula | Result |
|---|---|---|---|---|---|---|
| 12 | 2 | 3 | 8 | 20 | =ROUND(BETA.DIST(A2,B2,C2,TRUE,D2,E2),4) | 0.4074 |
| 15 | 2 | 3 | 8 | 20 | =ROUND(BETA.DIST(A3,B3,C3,TRUE,D3,E3),4) | 0.8011 |
| 0.3 | 2 | 5 | 0 | 1 | =ROUND(BETA.DIST(A4,B4,C4,TRUE,D4,E4),4) | 0.5798 |
Results calculated in Excel.
Mistakes people make
| Mistake | What to do instead |
|---|---|
| x outside A..B | #NUM!; check the bounds |
| Mixing up alpha and beta | Swapping them mirrors the curve |
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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