How to estimate your 1RM from a set with RPE
Add the reps you had left to the reps you did, then use the Epley formula: weight × (1 + reps ÷ 30). 405 lb for 3 at RPE 8 is 5 reps to failure, so the estimate is 405 × (1 + 5 ÷ 30) = 472.5 lb. Without RPE, the same set would read as 445.5 lb.
Why reps alone get it wrong
Rep-max formulas assume every set went to failure. Most training sets do not. A triple with two reps left read as a 3-rep max underestimates you; a grinder logged without RPE is at least read correctly. RPE fixes the first case by telling the formula how far from failure you stopped.
The formula RawLift uses
- Effective reps = reps + reps in reserve, where reps in reserve = 10 − RPE. No RPE: the set counts as all-out.
- Estimated 1RM = weight × (1 + effective reps ÷ 30), the Epley curve.
- Anchored at one: a true single (1 effective rep) counts as exactly its weight. Plain Epley would put a 200 kg single at 206.7 kg.
Worked examples
| Set | Effective reps | RawLift | Epley, no RPE | Brzycki, no RPE |
|---|---|---|---|---|
| 405 × 3 @ RPE 10 | 3 | 446 lb | 446 lb | 429 lb |
| 405 × 3 @ RPE 8 | 5 | 473 lb | 446 lb | 429 lb |
| 405 × 5, no RPE | 5 | 473 lb | 473 lb | 456 lb |
| 315 × 5 @ RPE 6 | 9 | 410 lb | 368 lb | 354 lb |
Brzycki, weight × 36 ÷ (37 − reps), reads lower than Epley at every rep count above one. The bigger difference comes from RPE: the easy set of 5 at RPE 6 says your max is around 410 lb, not 368 lb.
Which sets count
- Work sets only. A set marked as a warm-up never feeds the estimate.
- Sets rated RPE 6 or higher; below that you are too far from failure to tell.
- Up to 10 effective reps; beyond that it measures endurance more than strength.
- Your current max is the best session of the last six weeks, with the set it came from and a confidence level. Without a set in that window, RawLift shows the newest one from the last 90 days, marked as old.
How honest is your RPE?
The estimate is only as good as the rating. Ratings get more accurate with experience and closer to failure, so the heaviest sets of the day make the best estimates. More in RPE vs RIR. Try your own sets in the 1RM calculator.
Questions
What is the most accurate 1RM formula?
No formula is accurate for everyone, and all of them get worse above about 10 reps. Accounting for how hard the set was matters more than the choice between Epley and Brzycki: a set of 3 with two reps left is not a 3-rep max.
How does RPE change a 1RM estimate?
RPE tells how many reps were left. RawLift adds them to the reps you did: 3 reps at RPE 8 count as 5 reps to failure. The estimate then treats the set as a 5-rep max instead of a 3-rep max.
Does a single count as my 1RM?
A single at RPE 10 is your 1RM. A single at RPE 8 counts as about 3 reps to failure, so RawLift estimates your max at 10 % above it.
Which sets does RawLift ignore?
Warm-ups, sets rated below RPE 6 and sets worth more than 10 reps to failure. Those say more about warm-up or endurance than about your max. The estimate uses the best session of the last six weeks.
Sources
- Epley, B. (1985). Poundage Chart. Boyd Epley Workout. Lincoln, NE.
- Brzycki, M. (1993). Strength testing: predicting a one-rep max from reps-to-fatigue. Journal of Physical Education, Recreation & Dance, 64(1), 88–90.
- 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.
- 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.