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TDIST Function
Summary
The TDIST function calculates probability values for the Student t-distribution, essential for statistical hypothesis testing with small sample datasets. It provides the percentage points (probability) for a given t-value, serving as a digital alternative to traditional t-distribution tables.
Syntax
TDIST(x, deg_freedom, tails)Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
| x | Number |
Yes | The t-value at which to calculate the distribution probability |
| deg_freedom | Integer |
Yes | Number of degrees of freedom (integer ≥ 1) |
| tails | Integer |
Yes | Distribution tails: 1 (one-tailed) or 2 (two-tailed) |
Using the TDIST Function
TDIST is primarily used in statistical analysis for calculating p-values in t-tests. It helps determine the probability of observing a t-statistic as extreme as the one calculated from sample data under the null hypothesis.
Common TDIST Examples
Two-Tailed Distribution Example
=TDIST(1.96,60,2)Returns approximately 0.0546 (5.46%) - probability of t-statistic ≥ 1.96 or ≤ -1.96 with 60 degrees of freedom
One-Tailed Distribution Example
=TDIST(1.96,60,1)Returns approximately 0.0273 (2.73%) - probability of t-statistic ≥ 1.96 with 60 degrees of freedom
Frequently Asked Questions
Common Errors and Solutions
#VALUE!
Cause: Non-numeric input
Solution: Ensure all arguments are numeric
#NUM!
Cause: deg_freedom < 1 or tails not 1/2 or x < 0
Solution: Verify deg_freedom ≥ 1, tails is 1 or 2, x ≥ 0
Notes
- TDIST(x,df,1) = P(X > x)
- TDIST(x,df,2) = P(|X| > x) = P(X > x or X < -x)
- Function deprecated but available for backward compatibility
- Consider T.DIST.2T for two-tailed, T.DIST.RT for right-tailed tests
Compatibility
Available in: Excel 2007+, Excel 2010+, Excel 2013+, Excel 2016+, Excel 2019+, Excel 365+
Not available in: Excel 2003 and earlier
Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+, Excel 2010+, Excel 2013+, Excel 2016+, Excel 2019+, Excel 365+