Reps in Reserve Calculator

About this calculator

Reps in reserve (RIR) is a subjective rating of how many more reps you could have performed before technical failure on a given set — an RIR of 2 on a set of 8 means you could have done roughly 10 reps total. Combined with the actual weight and rep count performed, RIR feeds into standard percentage-of-1RM rep tables (built from the relationship between reps-to-failure and %1RM) to back out an estimated true one-rep max without ever testing a single all-out lift.

Strength coaches and lifters using autoregulated training programs rely on RIR-based 1RM estimation because it updates automatically as fatigue, sleep and recovery change how a given weight feels day to day — a maxing-out session isn’t required to know approximately where your 1RM currently stands, which matters because true 1RM tests carry injury risk and take a toll on recovery that most training blocks don’t need to pay.

This calculator takes the weight, reps completed and RIR of a set and returns your estimated one-rep max.