RPE calculator
Enter a set, rate it by RPE or reps in reserve, and get your estimated 1RM plus the working weight for any rep and RPE target. A set you stopped short of failure still tells you what you are capable of.
Estimated one-rep max
123.3 kg
5 reps at RPE 8 is 81.1% of your 1RM.
Working weights
From your estimated 1RM, rounded to the nearest 2.5 kg.
| Reps | RPE 100 RIR | RPE 91 RIR | RPE 82 RIR | RPE 73 RIR | RPE 64 RIR |
|---|---|---|---|---|---|
| 1 | 122.5 | 117.5 | 112.5 | 110 | 107.5 |
| 2 | 117.5 | 112.5 | 110 | 107.5 | 102.5 |
| 3 | 112.5 | 110 | 107.5 | 102.5 | 100 |
| 4 | 110 | 107.5 | 102.5 | 100 | 97.5 |
| 5 | 107.5 | 102.5 | 100 | 97.5 | 95 |
| 6 | 102.5 | 100 | 97.5 | 95 | 90 |
| 8 | 97.5 | 95 | 90 | 87.5 | 85 |
| 10 | 90 | 87.5 | 85 | 80 | 77.5 |
| 12 | 85 | 80 | 77.5 | 75 | 70 |
How the calculator works
The scale is the reps-in-reserve version of RPE used in strength training: RPE 10 means nothing left, RPE 9 means one rep left, RPE 8 means two (Zourdos et al., 2016). The maths runs in four steps:
- 1Reps in reserve = 10 − RPE. RPE 8 is 2 RIR.
- 2Reps to failure = reps done + reps in reserve. 5 reps at RPE 8 is 7 reps to failure.
- 3%1RM = the chart value for that many reps to failure. 7 reps to failure is 81.1%.
- 4Estimated 1RM = weight ÷ %1RM. 100 kg ÷ 0.811 = 123.3 kg.
The working-weight table runs the same chart in reverse: your estimated 1RM multiplied by the percentage for the target reps and RPE. That is how an RPE-based program turns “3 × 5 at RPE 8” into a number on the bar.
Assumptions
- —Your rating is honest. The estimate is only as good as the RPE you give it.
- —The set was one continuous set, not a cluster or rest-pause set.
- —The chart's percentages fit you. They are an average; some lifters hold a higher share of their max for more reps than others, and the profile differs between lifts.
- —Reps run from 1 to 12 and RPE from 6 to 10. Beyond that, ratings are too loose to price a max from.
The RPE chart
Every number the calculator uses. Read across for reps, down for effort. Every cell is one ladder: 3 reps at RPE 8 and 5 reps at RPE 10 are both 5 reps to failure, so both sit at 86.3%.
| RPE | RIR | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 10 | 0 | 100.0 | 95.5 | 92.2 | 89.2 | 86.3 | 83.7 | 81.1 | 78.6 | 76.2 | 73.9 | 70.7 | 68.0 |
| 9.5 | 0.5 | 97.8 | 93.9 | 90.7 | 87.8 | 85.0 | 82.4 | 79.9 | 77.4 | 75.1 | 72.3 | 69.4 | 66.7 |
| 9 | 1 | 95.5 | 92.2 | 89.2 | 86.3 | 83.7 | 81.1 | 78.6 | 76.2 | 73.9 | 70.7 | 68.0 | 65.3 |
| 8.5 | 1.5 | 93.9 | 90.7 | 87.8 | 85.0 | 82.4 | 79.9 | 77.4 | 75.1 | 72.3 | 69.4 | 66.7 | 64.0 |
| 8 | 2 | 92.2 | 89.2 | 86.3 | 83.7 | 81.1 | 78.6 | 76.2 | 73.9 | 70.7 | 68.0 | 65.3 | 62.6 |
| 7.5 | 2.5 | 90.7 | 87.8 | 85.0 | 82.4 | 79.9 | 77.4 | 75.1 | 72.3 | 69.4 | 66.7 | 64.0 | 61.3 |
| 7 | 3 | 89.2 | 86.3 | 83.7 | 81.1 | 78.6 | 76.2 | 73.9 | 70.7 | 68.0 | 65.3 | 62.6 | 59.9 |
| 6.5 | 3.5 | 87.8 | 85.0 | 82.4 | 79.9 | 77.4 | 75.1 | 72.3 | 69.4 | 66.7 | 64.0 | 61.3 | 58.6 |
| 6 | 4 | 86.3 | 83.7 | 81.1 | 78.6 | 76.2 | 73.9 | 70.7 | 68.0 | 65.3 | 62.6 | 59.9 | 57.4 |
Columns are reps completed. Cells are % of one-rep max.
New to rating sets? The RIR and RPE guide covers what each number feels like and how to rate honestly. If your set went to failure, the one rep max calculator is the better tool.
Every hard set, scored
In PRE SZN, a hard set is any working set at RIR 1–3. The app estimates a 1RM from every one of them and scores it against your own trailing four-week average for that exercise. Beat your average, take the point. A record always pays. Programs such as PRE SZN Power Build (RPE 8 daily singles) and the hypertrophy mesocycle (RIR targets that tighten week on week) run on exactly this scale.
Questions
How do I calculate 1RM from RPE?
Turn the RPE into reps in reserve (RIR = 10 − RPE), add those to the reps you did to get reps to failure, read the %1RM for that number off the chart, then divide the weight by it. 100 kg for 5 at RPE 8 is 7 reps to failure, 81.1% of max, so an estimated 1RM of about 123 kg.
What is the difference between RPE and RIR?
They are the same scale read from opposite ends. RIR counts the reps you had left; RPE counts down from 10. RPE 10 is 0 RIR, RPE 9 is 1 RIR, RPE 8 is 2 RIR. Half points such as RPE 8.5 mean you might have had one more rep, and definitely not three.
How accurate is an RPE-based 1RM estimate?
As accurate as the rating. The chart is an average; your own rep-max profile can differ between lifts. Ratings are most reliable on heavier sets of 12 reps or fewer and on sets close to failure, which is why the calculator stops at 12 reps and RPE 6.
Why does the working-weight table round the numbers?
Because you load plates, not decimals. Kilogram weights round to the nearest 2.5 kg and pound weights to the nearest 5 lb. The estimated 1RM above the table is shown unrounded.
How is this different from the one rep max calculator?
The one rep max calculator assumes the set went to failure and uses a blend of the Epley, Brzycki and Wathan formulas. This calculator takes your effort rating into account, so a set you stopped short of failure still gives a fair estimate.
Sources
- Zourdos MC et al. (2016). Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. J Strength Cond Res 30(1):267–275. doi:10.1519/JSC.0000000000001049
- Helms ER et al. (2016). Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength Cond J 38(4):42–49. doi:10.1519/SSC.0000000000000218
- Halperin I et al. (2022). Accuracy in predicting repetitions to task failure in resistance exercise. Sports Med 52(2):377–390. doi:10.1007/s40279-021-01559-x