T.INV Function in Excel: t Value for a Left-Tail Probability

T.INV Function in Excel: t Value for a Left-Tail Probability 1
⏱ 1 min readUpdated 5 October 2026

StatisticsLevel: ExpertAvailable in: Excel 2010+

In this article
  1. Syntax
  2. Examples
  3. Example 1
  4. T.INV in practice
  5. Where you will use it
  6. Worked example
  7. Mistakes people make
  8. Related functions

T.INV returns the t value for a left-tail probability; T.INV.2T is the usual critical value.

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Syntax

=T.INV(probability, deg_freedom)
Argument What it means
probability 0..1
deg_freedom df

Examples

Example 1

=ROUND(T.INV(A2,B2),4)

Result: -1.8125. See the worked example table below for more cases.

T.INV in practice

Where you will use it

  • One-sided critical values
  • Teaching
  • Simulation

Worked example

pdfFormulaResult
0.0510=ROUND(T.INV(A2,B2),4)-1.8125
0.9510=ROUND(T.INV(A3,B3),4)1.8125
0.510=ROUND(T.INV(A4,B4),4)0

Results calculated in Excel.

Mistakes people make

MistakeWhat to do instead
Wanting ± criticalUse T.INV.2T
p outside 0..1#NUM!

T.INV.2T

📚 Part of the free Excel course: Beginner → Expert · Try it in the Formula Lab or ask the AI Helper.

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