RPE and RIR Explained
What RPE and reps in reserve mean, how the RIR-based RPE scale works, and how to use it to manage effort and progression.
The short answer
RIR (reps in reserve) is how many more good reps you could have done. RPE 10 means no reps left; RPE 8 means about two left. They let you train hard enough without needing to hit failure.
The scale
The RIR-based RPE scale was proposed so lifters could adjust loads set by set to their capabilities on the day, and it may gauge intensity more accurately near maximal loads.
- RPE 10 — maximal, no reps left (0 RIR)
- RPE 9 — 1 rep left
- RPE 8 — 2 reps left
- RPE 7 — 3 reps left
- RPE 6 or less — easy, warm-up territory
Evidence: [1]
How to use it
Because taking every set to failure has not shown an advantage for muscle growth, an RPE 7–9 range is a practical target.
- Prescribe working sets at RPE 7–9 for most training.
- If a set planned at RPE 8 feels like RPE 10, reduce the load for the next set.
- Write the RPE down — it shows progress even on days the load does not change.
Evidence: [2]
Common mistakes
- Rating sets by how unpleasant they felt rather than reps left.
- Using RPE only on the main lift and ignoring it everywhere else.
Bottom line
Rate each set by how many good reps were left; keep most work at 1–3 reps in reserve.
References
- [1] Helms ER, Cronin J, Storey A, Zourdos MC. Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength and Conditioning Journal. 2016;38(4):42–49. Narrative review / practical application doi.org/10.1519/SSC.0000000000000218
- [2] Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ. Influence of resistance training proximity-to-failure on skeletal muscle hypertrophy: a systematic review with meta-analysis. Sports Medicine. 2023;53(3):649–665. Systematic review and meta-analysis doi.org/10.1007/s40279-022-01784-y
This guide summarises published research for healthy adults. It is general information, not medical advice — if you have a health condition, injury or take medication, talk to a qualified professional before changing your training or supplements.