How to use it
Enter the weight you lifted and the reps you managed on a hard set — ideally one you stopped a rep or two short of failure. The calculator instantly estimates your one rep max and builds a %-of-1RM table so you know what to load for any rep target. No calculate button.
Pick your lift to label the result — the same maths covers bench, squat, deadlift and overhead press. Tap Go advanced to see the Epley, Brzycki and Lombardi estimates side by side, plus their average.
Bench, squat & deadlift
1RM formulas don't care which lift you're doing, so this works as a bench press 1RM calculator, a squat one rep max calculator and a deadlift 1RM calculator all at once. Deadlifts and squats often estimate slightly high from high-rep sets because grip and technique fail before the muscles do — keep test sets heavy for accuracy.
Programming by percentage
Most strength programmes are written as percentages of your 1RM: heavy singles near 90–100%, strength work around 80–90%, hypertrophy around 67–80%. The training table on the right turns your estimated max into real bar weights for each rep range.
Track the rest of your training
Dial in conditioning with our Heart Rate Zone Calculator, set eating targets with the TDEE Calculator, or check body composition with the Body Fat Calculator.
The formulas we use
| Formula | Estimate of 1RM |
|---|---|
| Epley (default) | w × (1 + reps ÷ 30) |
| Brzycki | w ÷ (1.0278 − 0.0278 × reps) |
| Lombardi | w × reps^0.10 |
w is the weight lifted and reps the number completed. Epley and Brzycki agree closely at low reps; the three diverge as reps climb, which is why heavy sets give the truest estimate.
Percent-of-1RM guide
| Reps | ≈ % of 1RM |
|---|---|
| 1 | 100% |
| 3 | 94% |
| 5 | 89% |
| 8 | 81% |
| 10 | 75% |
| 12 | 71% |
Use the live table on the calculator for the exact weights from your own 1RM.
Common questions
How is one rep max calculated?
From the weight and reps of a set taken close to failure. The default Epley formula is 1RM = weight × (1 + reps ÷ 30) — so 100 kg for 5 reps estimates about 117 kg. Advanced mode also shows Brzycki, Lombardi and their average.
Does this work for bench, squat and deadlift?
Yes. The formulas are lift-agnostic, so the same calculator estimates 1RM for bench press, squat, deadlift, overhead press or any barbell lift. Pick the lift to label your result; the maths is identical.
How many reps give an accurate estimate?
Low reps are most accurate. A set of 1–5 reps predicts your true 1RM closely; beyond about 10–12 the error grows as endurance and technique take over. Use your heaviest honest set.
What is the percentage-of-1RM table for?
It converts your estimated 1RM into working weights for a target rep count — roughly 80% of 1RM for sets of 8, for example. Programmes are written as percentages of 1RM, so it tells you what to load on the bar.
Which formula is most accurate?
No single formula wins for everyone. Epley and Brzycki are the most used and agree at low reps; Lombardi runs higher on high-rep sets. Advanced shows all three plus their average — and the only definitive number is a tested single.