Reps in reserve: estimate what was left.

Learn what repetitions in reserve means, how RIR maps to set effort and why estimates improve with practice.

DIRECT ANSWER

Repetitions in reserve, or RIR, is an estimate of how many technically acceptable repetitions remained when a set ended. Zero RIR means no further acceptable repetition was available; two RIR means roughly two remained.

A practical scale

RIR turns set effort into a number that can travel with load and reps.

RIRPlain-language meaning
0No further acceptable repetition.
1About one repetition remained.
2About two repetitions remained.
3+A clearly submaximal set.

Accuracy is learned

RIR is subjective. Experience, exercise choice, rep range and fatigue can change estimate quality. Treat it as useful context rather than an instrument reading.

How to calibrate

Occasionally compare a predicted RIR with a safe set taken closer to the planned stopping point. Record the miss, then use later sessions to improve the estimate without turning every set into a test.

Sources and further reading

  1. RIR reliability study
  2. Proximity-to-failure systematic review
Updated 7 August 2026Reviewed by James Wood, founder