One Rep Max CalculatorHow to use an RPE calculator
Do a set and rate it. Ask how many more reps you could have done. Subtract that from 10 to get the RPE. Enter the weight, reps and RPE. For example, 100 kg for 5 reps at RPE 8 means about 7 reps were possible. That points to a max near 120 kg.
Here is the math the tool uses:
% of max = (37 minus reps possible) / 36
Estimated max = weight / % of max
For 100 kg x 5 at RPE 8: reps possible = 5 + 2 = 7. Then (37 minus 7) / 36 = 83.3%. So 100 / 0.833 = 120 kg. The second part is the Brzycki formula, one of the seven on the one rep max page.
RPE and reps in reserve
The RPE scale used in lifting is based on reps in reserve (RIR): RPE 10 means 0 reps left, RPE 9 means 1 rep left, and so on. Half points sit between. A 2016 study by Zourdos and others set out this scale and tested it with 29 lifters (Zourdos and others, 2016).
| RPE | What it means |
|---|---|
| 10 | Max effort. No reps left. |
| 9.5 | Between 0 and 1 rep left. |
| 9 | 1 rep left. |
| 8.5 | Between 1 and 2 reps left. |
| 8 | 2 reps left. |
| 7.5 | Between 2 and 3 reps left. |
| 7 | 3 reps left. |
| 5 to 6 | 4 to 6 reps left. |
In that study, higher RPE went with slower bar speed in both trained and new squatters. Trained squatters also rated their true max as harder than new squatters did. A 2016 review by Helms and others explains how to use this scale to adjust training loads from day to day (Helms and others, 2016).
RPE chart
This chart shows the percent of your max for each mix of reps and RPE, using the rule above.
| RPE | 1 rep | 2 reps | 3 reps | 4 reps | 5 reps | 6 reps | 7 reps | 8 reps | 9 reps | 10 reps |
|---|---|---|---|---|---|---|---|---|---|---|
| 10 | 100.0% | 97.2% | 94.4% | 91.7% | 88.9% | 86.1% | 83.3% | 80.6% | 77.8% | 75.0% |
| 9.5 | 98.6% | 95.8% | 93.1% | 90.3% | 87.5% | 84.7% | 81.9% | 79.2% | 76.4% | 73.6% |
| 9 | 97.2% | 94.4% | 91.7% | 88.9% | 86.1% | 83.3% | 80.6% | 77.8% | 75.0% | 72.2% |
| 8.5 | 95.8% | 93.1% | 90.3% | 87.5% | 84.7% | 81.9% | 79.2% | 76.4% | 73.6% | 70.8% |
| 8 | 94.4% | 91.7% | 88.9% | 86.1% | 83.3% | 80.6% | 77.8% | 75.0% | 72.2% | 69.4% |
| 7.5 | 93.1% | 90.3% | 87.5% | 84.7% | 81.9% | 79.2% | 76.4% | 73.6% | 70.8% | 68.1% |
| 7 | 91.7% | 88.9% | 86.1% | 83.3% | 80.6% | 77.8% | 75.0% | 72.2% | 69.4% | 66.7% |
| 6.5 | 90.3% | 87.5% | 84.7% | 81.9% | 79.2% | 76.4% | 73.6% | 70.8% | 68.1% | 65.3% |
| 6 | 88.9% | 86.1% | 83.3% | 80.6% | 77.8% | 75.0% | 72.2% | 69.4% | 66.7% | 63.9% |
This is one way to build the chart, not the only one. Charts made by coaches use their own tables, so their numbers can differ by a few percent. Pick one chart and use it every time.
Using the target set
Say your plan calls for 3 reps at RPE 9. That is 4 reps possible, or about 91.7% of max. With a 120 kg estimated max, the tool suggests about 110 kg. If the set feels easier or harder than planned, adjust the next set by a few percent.
More tools
Related guides
FAQ
What does RPE mean in lifting?
RPE stands for rating of perceived exertion. In lifting, it is scored from 1 to 10 based on how many reps you had left. RPE 10 means you could not do another rep. RPE 8 means you had about 2 reps left in the tank.
What is the difference between RPE and RIR?
RIR means reps in reserve, the reps you could still have done. RPE is 10 minus RIR. So 2 reps in reserve is RPE 8, and 1 rep in reserve is RPE 9. They are two ways to say the same thing.
How accurate is RPE?
A 2016 study of 29 squatters found that higher RPE ratings went with slower bar speed, a sign the ratings track real effort. The link was strong in both trained and new lifters. Rate every set and your sense of effort should sharpen.
Why does this chart differ from other RPE charts?
There is no single official RPE chart. This tool uses a clear rule: total possible reps equals reps done plus reps left, then the Brzycki formula turns that into a percent. Other charts use their own tables, so values can differ by a few percent.
References
- Zourdos MC et al. Novel resistance training specific rating of perceived exertion scale measuring repetitions in reserve. J Strength Cond Res. 2016 (PubMed)
- Helms ER et al. Application of the repetitions in reserve based rating of perceived exertion scale for resistance training. Strength Cond J. 2016 (PubMed)
- LeSuer DA et al. The accuracy of prediction equations for estimating 1RM performance in the bench press, squat, and deadlift. J Strength Cond Res. 1997;11(4):211-213