In this article
TDIST gives a one- or two-tailed t probability. It is a compatibility function: Excel keeps it so workbooks from Excel 2007 and earlier still calculate, but Microsoft recommends T.DIST.2T / T.DIST.RT for new work. Both give the same result.
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Syntax
=TDIST(x, deg_freedom, tails)| Argument | What it means |
|---|---|
x |
t (positive) |
deg_freedom |
df |
tails |
1 or 2 |
Examples
Example 1
=ROUND(TDIST(A2,B2,C2),4)Result: 0.0621. See the worked example table below for more cases.
💡 For new workbooks use T.DIST.2T / T.DIST.RT: it gives the same answer and is the name Microsoft keeps documenting.
TDIST in practice
Where you will use it
- Opening and checking older workbooks that use TDIST
- Understanding formulas shared by colleagues on older Excel versions
- Knowing when to swap in T.DIST.2T / T.DIST.RT for clarity
Worked example
| t | df | Tails | Formula | Result |
|---|---|---|---|---|
| 2.1 | 10 | 2 | =ROUND(TDIST(A2,B2,C2),4) | 0.0621 |
| 2.1 | 10 | 1 | =ROUND(TDIST(A3,B3,C3),4) | 0.031 |
| 1 | 20 | 2 | =ROUND(TDIST(A4,B4,C4),4) | 0.3293 |
Results calculated in Excel. Same result as T.DIST.2T / T.DIST.RT.
Mistakes people make
| Mistake | What to do instead |
|---|---|
| Using TDIST in new files | Prefer T.DIST.2T / T.DIST.RT: 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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