What is False Reject Rate (FRR)?

False Reject Rate (FRR) is the frequency at which a system denies access to the legitimate user during 1:1 verification. It is the mirror image of FAR, and typically acts in the opposite direction: Increasing threshold values leads to higher FRR, decreasing threshold values leads to higher FAR. There is no single “correct” value for either.

FRR is best managed with layered context. Keep liveness optimized so anti-spoofing measures don’t frustrate legitimate users; permit smart retakes; and route to secondary identity verification only when the risk/reward justifies it. Monitor FRR by device class and environment: Many “model” issues are actually camera- or lighting-related.

Blocked users remember unfair denials much longer than they remember frictionless logins. Consider FRR a customer-experience metric, not just a number on a chart.