RPE (rating of perceived exertion) describes how hard a set was on a scale from 1 to 10. In lifting, only the top end of the scale is really used: 10 means you couldn't have done another rep, 9 means you had one left, 8 means two left, and so on. RIR (reps in reserve) is the same idea counted the other way: how many reps you had left in the tank.
So RPE 8 = 2 RIR. RPE 10 = 0 RIR. Once that clicks, the rest is easy.
RPE and RIR scale
| RPE | RIR | What it feels like |
|---|---|---|
| 10 | 0 | Absolute max. Another rep was not happening, and your face agrees. |
| 9.5 | 0–1 | Maybe one more rep, or a little more weight. |
| 9 | 1 | One rep left. Hard, honest work. |
| 8.5 | 1–2 | Definitely one more, maybe two. |
| 8 | 2 | Two reps left. The sweet spot for most working sets. |
| 7 | 3 | Bar moves fast. Challenging but comfortable. |
| 6 and below | 4+ | Warm-up territory or speed work. |
RPE percentage chart
This chart shows roughly what percentage of your one-rep max you can lift for a given number of reps at a given RPE. Popularized by RPE-based powerlifting coaching, it's the same chart our RPE calculator uses.
| RPE | 1 rep | 2 reps | 3 reps | 4 reps | 5 reps | 6 reps | 7 reps | 8 reps | 9 reps | 10 reps |
|---|---|---|---|---|---|---|---|---|---|---|
| 10 | 100.0% | 95.5% | 92.2% | 89.2% | 86.3% | 83.7% | 81.1% | 78.6% | 76.2% | 73.9% |
| 9.5 | 97.8% | 93.8% | 90.7% | 87.8% | 85.0% | 82.4% | 79.8% | 77.4% | 75.1% | 72.3% |
| 9 | 95.5% | 92.2% | 89.2% | 86.3% | 83.7% | 81.1% | 78.6% | 76.2% | 73.9% | 70.7% |
| 8.5 | 93.8% | 90.7% | 87.8% | 85.0% | 82.4% | 79.8% | 77.4% | 75.1% | 72.3% | 69.3% |
| 8 | 92.2% | 89.2% | 86.3% | 83.7% | 81.1% | 78.6% | 76.2% | 73.9% | 70.7% | 68.0% |
| 7.5 | 90.7% | 87.8% | 85.0% | 82.4% | 79.8% | 77.4% | 75.1% | 72.3% | 69.3% | 66.8% |
| 7 | 89.2% | 86.3% | 83.7% | 81.1% | 78.6% | 76.2% | 73.9% | 70.7% | 68.0% | 65.5% |
| 6.5 | 87.8% | 85.0% | 82.4% | 79.8% | 77.4% | 75.1% | 72.3% | 69.3% | 66.8% | 64.2% |
| 6 | 86.3% | 83.7% | 81.1% | 78.6% | 76.2% | 73.9% | 70.7% | 68.0% | 65.5% | 63.0% |
How to read it: if your max is 300 lb and the program says 5 reps at RPE 8, find row 8, column 5: 81.1%. That's about 245 lb. Simple, and slightly more scientific than "whatever felt heavy last week".
Why RPE beats fixed percentages (sometimes)
Percentages assume you're equally strong every day. You're not. Bad sleep, a stressful week or a heroic leg day two days ago all change what you can lift. RPE adjusts to that: on a good day RPE 8 might be 250 lb, on a rough day 235 lb, and both are the right training stimulus. This is called autoregulation, and it's one of the most useful tools in strength training.
Percentages still have their place, especially for beginners who can't rate sets accurately yet. Many programs combine both: a percentage to set the starting weight, RPE to fine-tune.
How to rate RPE accurately
- Rate straight after the set. Memory gets generous quickly.
- Watch your bar speed. If the last rep slowed down a lot, you were probably at RPE 9 or above.
- Film your sets. The camera doesn't care about your feelings, which is exactly why it's useful.
- Test yourself occasionally. On a safe exercise, take a set you'd call RPE 8 and see if you really get 2 more reps. Most people find they had more in them.
What RPE should you train at?
For most strength and muscle-building goals, keep working sets between RPE 7 and 9. That's hard enough to drive progress but leaves enough in reserve to recover, keep form tight and train again soon. Save RPE 10 for testing and the occasional last set of an isolation exercise, where failure carries little risk.
Frequently asked questions
Is RPE the same as RIR?
They describe the same thing. RIR counts reps left; RPE rates effort out of 10. RPE = 10 − RIR.
Is RPE good for beginners?
Yes, as long as you know beginners tend to underestimate how many reps they have left. Rate every set anyway; you'll get better at it within a few weeks.
Who invented the RPE scale for lifting?
The RPE scale came from exercise science, and was adapted for lifting with reps in reserve by powerlifting coaches in the 2000s, most famously Mike Tuchscherer of Reactive Training Systems.
