Two sets of ten with the same weight can be completely different. One may feel comfortable; the other may be the last clean set you could possibly finish. Reps in reserve, or RIR, captures that difference.
A simple definition
RIR is your estimate of how many technically sound repetitions remained at the end of a set. If you could have performed two more good reps, record RIR 2. If no clean rep remained, that is RIR 0.
You do not need laboratory precision. Consistent estimates are useful because they add effort context to load and repetition data.
How to become more accurate
- Judge the set after you rack the weight, not before.
- Count only reps you could perform with the same technique.
- Compare the final repetition speed with earlier reps.
- Use the same scale across exercises and weeks.
Avoid turning every set into a test. Most productive training can leave a small margin, while still being challenging enough to progress.
Why AnyGear asks
RIR helps distinguish a load that was easy from one that was barely completed. That context can support more sensible progression and better interpretation of fatigue. Logging one honest number takes seconds and makes the rest of the record far more meaningful.
Evidence note
Research suggests trained lifters can estimate repetitions in reserve with useful but imperfect accuracy, and that accuracy varies by exercise and proximity to failure. See the four-exercise RIR study and a study of RIR-based load selection. Treat RIR as a repeatable field estimate, not an exact measurement.