1RM calculator with RPE
Your estimated one-rep max (1RM) is the most you could lift once, worked out from a lighter set. Enter the weight, the reps and, if you rated the set, its RPE. RPE keeps the estimate honest: 5 reps at RPE 8 had two more in the tank, so they are read as a 7-rep max.
Your rep maxes
What this 1RM means for the sets you program, rounded to 5 lb plates.
| Reps | All-out (RPE 10) | RPE 8 | % of 1RM at RPE 10 |
|---|---|---|---|
| 1 | 390 lb | 355 lb | 100.0 % |
| 2 | 365 lb | 345 lb | 93.8 % |
| 3 | 355 lb | 335 lb | 90.9 % |
| 4 | 345 lb | 325 lb | 88.2 % |
| 5 | 335 lb | 315 lb | 85.7 % |
| 6 | 325 lb | 305 lb | 83.3 % |
| 7 | 315 lb | 300 lb | 81.1 % |
| 8 | 305 lb | 290 lb | 78.9 % |
| 9 | 300 lb | 285 lb | 76.9 % |
| 10 | 290 lb | 280 lb | 75.0 % |
How the estimate is calculated
- Effective reps = reps + reps in reserve, where reps in reserve = 10 − RPE. 5 reps at RPE 8 are 7 effective reps. Without an RPE the set is treated as all-out.
- Share of 1RM = 1 ÷ (1 + effective reps ÷ 30), the Epley curve. For a single at RPE 10 it is exactly 100 %, and between one and two effective reps it is interpolated, so a true single never estimates above itself.
- Estimated 1RM = weight ÷ share of 1RM.
Plain Epley (weight × (1 + reps ÷ 30)) puts a 200 kg single at 206.7 kg, which makes no sense for a set that was already a max. Brzycki (weight × 36 ÷ (37 − reps)) runs lower than Epley at higher reps. Both ignore how hard the set was, which is the part RPE adds. The full reasoning, with worked examples, is in how to estimate your 1RM from a set with RPE.
Questions
How accurate is a 1RM calculator?
Close, within a few percent, for hard sets of 1 to 5 reps. Accuracy drops as reps rise, because endurance differs from lifter to lifter. Above about 10 reps an estimate says more about endurance than strength, which is why the RawLift app ignores sets worth more than 10 reps for your live max.
Why does RPE change my estimated 1RM?
Reps alone assume the set went to failure. Five reps at RPE 8 left about two reps in the tank, so the set shows the strength of a 7-rep max. Reading it as a 5-rep max would underestimate you; reading a grinder at RPE 10 as an easy set would overestimate you.
Which formula does this calculator use?
Epley from two reps on, anchored so that a true single counts as exactly its weight. RPE is converted to reps in reserve (10 minus RPE) and added to the reps. Plain Epley and Brzycki are shown next to it for comparison.
Should I test my 1RM or estimate it?
Most powerlifters max out rarely: at a meet or at the end of a training block. In between, an estimate from your regular top sets tracks progress week to week without the recovery cost of a true max.
Does it work for squat, bench and deadlift?
Yes, and for any lift you can rate honestly. Estimates are most reliable from low-rep sets of the competition lifts, which is how powerlifters train them anyway.
Sources
- Brzycki, M. (1993). Strength testing: predicting a one-rep max from reps-to-fatigue. JOPERD, 64(1), 88–90. doi:10.1080/07303084.1993.10606684
- Zourdos, M. C. et al. (2016). Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. Journal of Strength and Conditioning Research, 30(1), 267–275. doi:10.1519/JSC.0000000000001049
- Helms, E. R. et al. (2016). Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength and Conditioning Journal, 38(4), 42–49. doi:10.1519/SSC.0000000000000218
- Epley, B. (1985). Poundage chart. Boyd Epley Workout, University of Nebraska.