Returns the tvalue of the Student's tdistribution as a function of the probability and the degrees of freedom.
Syntax
TINV(probability,degrees_freedom)
Probability is the probability associated with the twotailed Student's tdistribution.
Degrees_freedom is the number of degrees of freedom to characterize the distribution.
Remarks

If either argument is nonnumeric, TINV returns the #VALUE! error value.

If probability < 0 or if probability > 1, TINV returns the #NUM! error value.

If degrees_freedom is not an integer, it is truncated.

If degrees_freedom < 1, TINV returns the #NUM! error value.

TINV is calculated as TINV = p( t<X ), where X is a random variable that follows the tdistribution.

A onetailed tvalue can be returned by replacing probability with 2*probability. For a probability of 0.05 and degrees of freedom of 10, the twotailed value is calculated with TINV(0.05,10), which returns 2.28139. The onetailed value for the same probability and degrees of freedom can be calculated with TINV(2*0.05,10), which returns 1.812462. In some tables, probability is described as (1p).
TINV uses an iterative technique for calculating the function. Given a probability value, TINV iterates until the result is accurate to within ± 3x10^7. If TINV does not converge after 100 iterations, the function returns the #N/A error value.
Example
Probability 
Degrees 
Formula 
Description (Result) 
0.054645 
60 
=TINV([Probability],[Degrees]) 
tvalue of the Student's tdistribution for the specified arguments (1.959997462) 