# Diagnostic Post Test Probability of Disease Calculator

Posttest probability is a type of subjective probability of a disease that turns out to be positive or negative depending on the result of the diagnostic test conducted. This online calculator computes the *post test probability* of a disease when the values of pretest probability and likelihood ratio are given

## Diagnostic Post Test Probability of Disease Calculation

Posttest probability is a type of subjective probability of a disease that turns out to be positive or negative depending on the result of the diagnostic test conducted. This online calculator computes the *post test probability* of a disease when the values of pretest probability and likelihood ratio are given

Code to add this calci to your website

**Formula:**
O = p1 / ( 1 - p1 ),
p2 = O * L,
p = p2 / ( 1 + p2 ),
Where,
p1 is the pretest probability,
O is the pretest odds,
p2 is the posttest odds,
L is the likelihood ratio,
p is the posttest probability.