IOA Calculator

Interobserver agreement (IOA) tells you how much two observers' data match. Pick a method, enter both observers' data, and get the agreement percentage with its formula. Everything runs in your browser. Nothing is uploaded.

Calculate agreement

IOA method

Observer A total count

Observer B total count

Many supervisors look for IOA of at least 80%. Lower agreement is a cue to retrain or tighten your operational definitions, not a failing grade.