One Rep Max Calculator
Estimate your one-rep max from a set, or the weight for any number of reps, with a percentage table.
Reps done with good form before failure.
Enter the weight lifted to see the result.
Estimates the heaviest weight you could lift once, your one-rep max (1RM), from a set you took close to failure, so you can plan training loads without testing a true max. It gives Epley's estimate with Brzycki's beside it, and a table of the weight and the reps to expect at each percentage from 50% to 100%. It also works the other way: from a max you know, the weight for a number of reps. Every calculation runs in your browser.
How to use it
One-rep max takes the weight lifted and the reps, from 1 to 30, done with good form. Weight for reps takes a known max and the reps wanted. Weights are in kg or lb; the unit is kept on your device and shared with the other health tools. Round weights down takes every weight shown down to a multiple of 2.5 kg or 5 lb, the smallest jump on most bars, so each set stays one you can finish; the table then counts the reps at the weight it shows.
How it works
Epley's formula adds a thirtieth of the weight for each rep. A single set of one rep is taken as the max itself, in every formula, since it is one. Brzycki's formula rises more slowly for low reps and faster past about ten, and its denominator reaches zero at 37 reps, which the 30-rep limit keeps well away from.
The table works Epley backwards: at a share p of your max, the reps are 30 × (1 ÷ p − 1), rounded down so the set is one you can finish, and never fewer than one. Weights are shown to 0.1 kg or the nearest pound unless rounding to plates is on.
Epley: 1RM = weight × (1 + reps ÷ 30)
Brzycki: 1RM = weight × 36 ÷ (37 − reps)
Reps at a share p of 1RM (Epley): 30 × (1 ÷ p − 1), rounded down
Examples
100 kg for 5 reps
Epley gives 116.7 kg and Brzycki 112.5 kg. With rounding to plates on, Epley's reads 115 kg.
225 lb for 8 reps
Epley gives 285 lb and Brzycki 279 lb.
A 140 kg max, for sets of 3
With Weight for reps, Epley puts the weight at 127.3 kg, or 125 kg rounded to plates.
Percentage of one-rep max
| % of 1RM | Weight | Reps |
|---|---|---|
| 100% | 100 kg | 1 |
| 95% | 95 kg | 1 |
| 90% | 90 kg | 3 |
| 85% | 85 kg | 5 |
| 80% | 80 kg | 7 |
| 75% | 75 kg | 10 |
| 70% | 70 kg | 12 |
| 65% | 65 kg | 16 |
| 60% | 60 kg | 20 |
| 55% | 55 kg | 24 |
| 50% | 50 kg | 30 |
Rules and sources
Epley's formula comes from the poundage chart in Boyd Epley's 1985 training manual, a coaching chart rather than a study. Brzycki set his out in 1993 in a practitioners' journal, for sets taken to fatigue. Both assume a set to failure; a set stopped short gives a lower estimate.
Later studies tested them. LeSuer and colleagues (1997) found seven equations, these two among them, closely correlated with tested maxes in untrained students, but most missed the average for the bench press and squat, and every one underestimated the deadlift. Reynolds and colleagues (2006) found sets of 5 reps predicted best, and advise no more than 10 reps for an estimate, so the calculator notes sets above that.
Sources
- Epley B. Poundage chart, in Boyd Epley Workout (Body Enterprises, Lincoln, Nebraska, 1985), as described in Marzagao T, A weight-dependent 1RM prediction equation (2026 preprint, not peer reviewed) — arXiv
- Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue (JOPERD 1993;64(1):88–90) — Journal of Physical Education, Recreation & Dance
- LeSuer DA et al. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift (J Strength Cond Res 1997;11(4):211–213) — Journal of Strength and Conditioning Research
- Reynolds JM, Gordon TJ, Robergs RA. Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry (J Strength Cond Res 2006;20(3):584–592) — Journal of Strength and Conditioning Research
Reviewed
Frequently asked questions
See also
- Calorie Calculator — the calories you burn in a day, for a training diet.
- Macro Calculator — protein, carbs and fat in grams for your goal.