RPE Calculator
Rate of Perceived Exertion turns "how heavy?" into a number you can program with. Enter a set and its RPE to estimate your one-rep max — then read off the exact loads to hit any rep count at any effort level. Built on reps-in-reserve percentages, the standard behind autoregulated training.
| Reps | Load at RPE 8 | % of 1RM |
|---|
How it works
Every RPE maps to reps in reserve — the reps you had left in the tank. RPE 10 is zero in reserve; RPE 8 is two. Add those reserve reps to the reps you actually did and you get an effective reps-to-failure figure. A set of 5 at RPE 8 is really 7 reps from failure — and 7 reps from failure corresponds to roughly 81% of your one-rep max on the standard reps-in-reserve chart. Divide your weight by that percentage and you have an estimated 1RM.
The target-load table runs the same math backwards: from your estimated max, it prints the weight that will land at your chosen RPE for 1, 2, 3, 5, 8, 10, and 12 reps. Change the RPE dropdown to re-price the whole table for that effort.
The RPE scale
| RPE | Meaning | Reps in reserve |
|---|---|---|
| 10 | Maximal — nothing left | 0 |
| 9 | One rep left | 1 |
| 8 | Two reps left — hard but crisp | 2 |
| 7 | Three reps left — bar moves fast | 3 |
| 6 | Speed and technique work | 4+ |
For the full breakdown — half-points, calibration, and where to program each RPE — see the RPE Explained guide.
How to use the loads
Most productive training lives between RPE 7 and 9. A common pattern: heavy compounds at RPE 7–8 to protect form and recovery, isolation work at RPE 8–9 where the fatigue cost is low. Set the dropdown to your target and use the table as a starting weight — then trust your body over the number. If "5 reps at RPE 8" says 82.5 kg but the bar flies up, add weight; if it grinds, take some off. That self-correction is the entire point of training by effort.
A note on accuracy
Two honest caveats. First, RPE-to-percentage charts are population averages — your personal numbers may run a few points either way, especially on different lifts. Second, RPE ratings are a skill: newer lifters tend to underrate effort, calling a set RPE 8 when four reps were left. Both estimates sharpen as you log more sets and compare predictions to reality. Treat every number here as a well-educated starting point, not a verdict.
FAQ
What is RPE in weightlifting?
Rate of Perceived Exertion — a 1–10 rating of how hard a set felt, anchored to reps in reserve. RPE 10 means no reps left; RPE 8 means about two. It lets you program by effort instead of fixed percentages. Full detail in the RPE guide.
How does an RPE calculator estimate 1RM?
It turns your RPE into reps in reserve, adds them to your reps for an effective reps-to-failure figure, finds the matching percentage of 1RM, and divides your weight by it. Prefer a pure formula? Try the 1RM calculator.
What weight should I use for a given RPE?
Estimate your 1RM above, then read the target-load table for your chosen RPE and rep count. On the day, adjust until the set truly lands at that effort.
Is RPE better than percentage-based training?
For most lifters, yes — because your true max drifts day to day with sleep and stress, and RPE self-adjusts to the body that showed up. Percentages make a fine starting estimate; RPE fine-tunes it.
Herculog puts an RPE field on every logged set, and plans from the Plan Builder carry their RPE targets into the app — so "3×8 @ RPE 8" is right there while you decide whether to add weight.
More free tools
Estimate a one-rep max, load the bar, or plan your warmups — all private, all in the browser.