One-rep max (1RM) from a set of reps with the Epley, Brzycki, Lombardi and O'Conner equations, plus training loads from 50 % to 100 %.
100 kg for 5 reps points to a one-rep max of about 114.8 kg (253.1 lb); the four equations range from 112.5 to 117.5 kg.
| % of 1RM | kg | lb | Reps (Epley) |
|---|---|---|---|
| 100 % | 114.8 | 253.1 | 1 |
| 95 % | 109 | 240.4 | 2 |
| 90 % | 103.3 | 227.7 | 3 |
| 85 % | 97.6 | 215.1 | 5 |
| 80 % | 91.8 | 202.4 | 8 |
| 75 % | 86.1 | 189.8 | 10 |
| 70 % | 80.3 | 177.1 | 13 |
| 65 % | 74.6 | 164.5 | 16 |
| 60 % | 68.9 | 151.8 | 20 |
| 55 % | 63.1 | 139.2 | 25 |
| 50 % | 57.4 | 126.5 | 30 |
Loads are in kilograms; pounds are converted at 1 lb = 0.45359237 kg.
A one-rep max (1RM) is the heaviest load you can lift once with good form. It is estimated here from a set taken to failure with four equations: Epley, weight × (1 + reps ÷ 30); Brzycki, weight × 36 ÷ (37 − reps); Lombardi, weight × reps^0.10; and O'Conner, weight × (1 + 0.025 × reps). The main result is their mean, shown in kilograms and pounds.
Lifters use it to set training loads without a maximal attempt. With the default 100 kg for 5 reps, the four equations give 112.5 to 117.5 kg and a mean of 114.8 kg; the table then lists loads from 50 % to 100 % of that, with the reps Epley predicts at each.
The equations were fitted to groups of lifters and lose accuracy as reps rise, especially past 10. They are lift-specific, so an estimate from the bench press says nothing about the squat.
Checked against: Python 3.8 decimal/math: 100(1 + 5/30), 100·36/32, 100·5^0.1, 100(1 + 0.125); mean of the four
Checked against: Python 3.8 decimal: 225 lb = 102.0582833 kg; Epley 300 lb = 136.0777 kg; Lombardi 225·10^0.1 lb; mean 291.127 lb
Checked against: Convention stated in the steps: r = 1 returns the lifted weight for every equation (Brzycki and Lombardi give it exactly)
Checked against: Python 3.8 decimal/math: 60·1.4, 60·36/25, 60·12^0.1, 60·1.3; mean 81.3313
Lift a weight for as many clean reps as possible in one set, then apply an equation. Epley's is weight × (1 + reps ÷ 30), so 100 kg for 5 reps gives 116.7 kg; Brzycki's is weight × 36 ÷ (37 − reps), giving 112.5 kg. This calculator averages Epley, Brzycki, Lombardi and O'Conner, which gives 114.8 kg for that set.
None is best for every lift or lifter, and they agree most at low reps. For 100 kg lifted 5 times the four span 112.5 to 117.5 kg, a 5 kg spread; for 60 kg lifted 12 times they span 76.9 to 86.4 kg, almost 10 kg. Estimates from sets of 10 reps or fewer are therefore more consistent, and the mean used here sits between the highest and lowest equation.
About 8, by the Epley equation solved for reps: 30 × (100 ÷ 80 − 1) = 7.5, rounded to 8. The table under the result lists loads and Epley rep estimates from 50 % to 100 %: at 90 % it gives 3 reps and at 70 % it gives 13. Real rep counts at a given percentage vary between lifts and between lifters.
Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 4 worked examples whose answers come from independent sources; for example, “100 kg for 5 reps” is checked against Python 3.8 decimal/math: 100(1 + 5/30), 100·36/32, 100·5^0.1, 100(1 + 0.125); mean of the four.
LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. 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; Brzycki M. Strength testing — predicting a one-rep max from reps-to-fatigue. J Phys Educ Recreat Dance 1993;64(1):88–90; Epley B. Poundage chart. Boyd Epley Workout. Lincoln, NE: Body Enterprises; 1985.
4 worked examples with independently sourced answers ship with this calculator. They run in the test suite; you can run them here too.
Calories burned by an activity from its MET value in the Compendium of Physical Activities, your body weight and the time spent.
Daily protein intake in grams from body weight, goal and training level, using published g/kg ranges, with a per-meal split.
Lean body mass (LBM) from height, weight and sex by the Boer, James and Hume formulas, with the implied body fat percentage.
Heart rate zones from your maximum heart rate (220 − age, Tanaka, Gulati for women, or measured) by the Karvonen or percent-of-max method, with a target heart rate.
VO2 max from the Cooper 12-minute run, the Rockport 1-mile walk or the resting heart-rate ratio, rated against Cooper Institute norms for age and sex.
Running pace per km or mile from distance and time, or finish time or distance from pace, with even splits and Riegel race predictions.
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