RPE calculator
Turn RPE into a practical load estimate without pretending effort ratings are laboratory instruments.
Turn RPE into loading targets
Use it after a set, then let your next set confirm whether the estimate was honest.
| Target | Load |
|---|---|
| 3 reps @ RPE 8 | 105.7 kg |
| 5 reps @ RPE 8 | 100 kg |
| 8 reps @ RPE 8 | 92.5 kg |
| 5 reps @ RPE 9 | 102.8 kg |
The useful number, with the asterisks left in
What this number means
In strength training, RPE is usually used as an effort rating tied to reps in reserve. RPE 10 means no reps left, RPE 9 means about one rep left, and so on.
The calculator turns that effort rating into an estimated one-rep max and a small target-load table for nearby training prescriptions.
What it does not know
RPE is a skill. New lifters often misjudge how many reps they had left, and even experienced lifters can be off when tired, stressed, rushed, or doing unfamiliar movements.
The output assumes your set was performed with consistent technique and that your RPE rating is close enough to be useful.
How to use it
Use RPE to adjust a plan to the day you are actually having. If warmups feel heavy, the same target RPE should lead to a lower load; if everything moves well, it may let you go heavier.
For most training, use the output as a loading suggestion, then let bar speed, technique, and next-set performance confirm or correct it.
When not to trust it
Do not use RPE estimates from sets far from failure as proof of a new max. A set of 8 at RPE 6 can be useful, but the uncertainty is larger than a hard top set.
Pain, unusual fatigue, or major technique changes should override the calculator.
Caveats
- RPE-to-RIR mapping is a practical coaching model, not a direct measurement.
- Best used with repeat exposure to the same lift and rep range.
- The calculator accepts RPE 5 to 10 because lower effort ratings become too uncertain for max estimates.
Examples
- 100 kg for 5 reps at RPE 8 implies about 2 reps in reserve.
- A 5-rep set at RPE 8 estimates max from about 7 effective reps.
Where the method comes from
- Borg G. Psychophysical bases of perceived exertion. Medicine and Science in Sports and Exercise. 1982.
- Zourdos et al. Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. Journal of Strength and Conditioning Research. 2016.
- CDC. How to Measure Physical Activity Intensity.