RPE (Rating of Perceived Exertion) adapts the Borg scale from exercise physiology for powerlifting and strength training. It rates how much you had left in the tank on a given set, on a 10-point scale, and forms the basis of autoregulation — adjusting your training load to how you feel each day.
How to use this tool
Right after a set, enter the weight and reps you performed along with the RPE for that set. The RIR (reps in reserve) implied by your RPE is added to your rep count to get an "effective rep max", which is then run through the same Epley formula used on the 1RM Calculator. Unlike a standard 1RM calculator, which assumes the set was taken to failure, this tool also works for sets stopped short of failure.
Reading your results
"%1RM" shows what percentage of your estimated 1RM today's weight represents. A common approach is to train most sets around RPE 8-9 and occasionally push to RPE 9.5-10 to test your limits. The Interval Calculator can help with rest times between sets.
Getting better at RPE
It's normal to be inaccurate at first. Practise estimating reps in reserve after every set, then compare against days you actually trained to failure to calibrate your sense over several weeks to months. A good rule of thumb is to gauge it against the point where your form starts to break down.
| RPE | 10 | 9.5 | 9 | 8.5 | 8 | 7.5 | 7 | 6.5 | 6 |
|---|---|---|---|---|---|---|---|---|---|
| RIR | 0 | 0.5 | 1 | 1.5 | 2 | 2.5 | 3 | 3.5 | 4 |
RIR (Reps in Reserve) = how many more reps you could have done. RPE = 10 − RIR (Helms et al. 2016). This tool uses "reps + RIR" as the effective rep max for 1RM estimation.
What is RPE?+
RPE 10: could not do another rep RPE 9: one rep left RPE 7: about three reps left
It is widely used in powerlifting and strength training.
What is the difference between RPE and RIR?+
RIR = 10 − RPE
RPE 8 means RIR 2 (two reps left), RPE 10 means RIR 0 (failure). This tool uses RIR to back-calculate your effective max reps and estimate your 1RM.
How is this different from a regular 1RM calculator?+
This tool factors in RPE (how much was left in the tank), working out how many reps you could have done to failure (reps + RIR) before estimating your 1RM — so it also works for sets stopped short of failure.
How do I get better at estimating RPE?+
When is RPE useful?+
· Helms ER, Cronin J, Storey A, Zourdos MC. Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training. Strength Cond J. 2016;38(4):42-49. (RPE-RIR scale)
· Zourdos MC, et al. Novel Resistance Training-Specific RPE Scale Measuring Repetitions in Reserve. J Strength Cond Res. 2016;30(1):267-275.
· Epley B. Poundage chart. Boyd Epley Workout. 1985. (1RM estimation from effective reps)
RPE is a subjective measure and its accuracy depends on training experience and how well you read your own body. If your form breaks down or you feel joint pain, stop regardless of the RPE reading. This tool is for informational purposes only and does not replace professional coaching.
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