What Is Reps in Reserve (RIR)?
Reps in Reserve is a subjective measure of how many more repetitions you could have completed before reaching muscular failure. It was formalized by Zourdos et al. (2016) as a way to quantify effort in resistance training.
RIR directly maps to the RPE (Rating of Perceived Exertion) scale used in powerlifting, where RPE 10 = 0 RIR (maximal effort) and RPE 6 = 4+ RIR (light effort). This converter lets you translate between the two systems instantly.
RPE and %1RM Estimation
When you know both RPE and the number of reps performed, you can estimate the percentage of your one-rep max (%1RM) that was lifted. This is based on the Tuchscherer / RTS RPE chart, widely used in powerlifting programming.
For example, 5 reps at RPE 8 corresponds to approximately 82% of your 1RM. If your 1RM is 100 kg, the suggested working weight would be about 82 kg. For direct 1RM estimation, see the One Rep Max Calculator or the RPE to 1RM Calculator.
Practical Applications
- Autoregulation — Use RPE/RIR to adjust working weight based on daily readiness rather than fixed percentages
- Progressive overload — Gradually reduce RIR from 3-4 to 0-1 over a training block. Track this with the Progressive Overload Calculator
- Volume planning — Higher RIR allows more sets before fatigue accumulates. Monitor with the Volume-to-Intensity Ratio Calculator
Frequently Asked Questions
Sources & References
- Novel Resistance Training-Specific RPE Scale Measuring Repetitions in Reserve. Zourdos MC et al.. Journal of Strength and Conditioning Research (2016)
- Efficacy of the Repetitions in Reserve-Based RPE for the Bench Press. Ormsbee MJ, Carzoli JP, Klemp A et al.. Journal of Strength and Conditioning Research (2019)
- RPE and RIR: The Complete Guide. Mass Research Review. Mass Research Review (2023)
Disclaimer: This tool is for informational and personal journaling purposes only. Results are estimates based on published formulas and may vary based on individual factors such as genetics, training history, and measurement technique.
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