One-rep max calculator

Estimate your one-rep max from a set of several reps, without testing a single. The rep-max table turns the estimate into loads for other rep counts.

This calculator runs in your browser and needs JavaScript. The method below gives the same formula to work by hand.

Input / Set

Units

Metric

Imperial

Weight lifted

Reps

Reps completed in the set.

Reps left in reserve

Optional. How many more reps you could have done. Leave it empty for a set to failure.

Result / One-rep maxEpley

No input

Enter the weight and the reps of a hard set to see your estimated one-rep max.

How it is calculated

This calculator estimates a one-rep max (e1RM) the way Pendum Lift does. Reps left in reserve count as reps you could have done, so 5 reps with 2 in reserve is 7 reps to failure. An empty reserve field counts as 0, a set taken to failure.

The estimate is the Epley equation on reps to failure. At 1 rep to failure it is the weight itself. Kilograms and pounds give the same answer in their own unit.

reps to failure = reps + reps in reserve

e1RM = weight
  × (1 + reps to failure / 30)
e1RM = weight   (1 rep to failure)

The rep-max table runs Epley backwards. The load for r reps to failure is the e1RM divided by (1 + r / 30), and the e1RM itself at 1 rep. The percentage is that load as a share of the e1RM: 94% for 2 reps, 86% for 5 and 75% for 10. The table counts reps to failure, so the row marked as your set is your reps plus your reserve: 7 for 5 reps with 2 in reserve.

load(r) = e1RM / (1 + r / 30)
r = 2 to 12 reps to failure

Rep-max percentages (Epley)

Share of the one-rep max for 1 to 12 reps to failure, with the load at a 100 kg one-rep max
Reps to failure	% of 1RM	Load at 100 kg
1	100%	100.0 kg
2	94%	93.8 kg
3	91%	90.9 kg
4	88%	88.2 kg
5	86%	85.7 kg
6	83%	83.3 kg
7	81%	81.1 kg
8	79%	78.9 kg
9	77%	76.9 kg
10	75%	75.0 kg
11	73%	73.2 kg
12	71%	71.4 kg

Reps to failure, so a set of 5 with 2 in reserve is the 7-rep row. The loads are for an e1RM of 100 kg, so they read as percentages in any unit; the tool fills the same table from your own set.

Brzycki is shown for comparison up to 10 reps to failure, on the same reps to failure. From 2 to 9 reps it reads a little lower than Epley, and the two agree at 1 and at 10 reps. Past 10 the Brzycki denominator shrinks quickly and its estimate climbs, so it is left out.

Brzycki = weight × 36
  / (37 − reps to failure)

Rep-based equations track measured maxes well on average but can miss for one person. LeSuer and colleagues compared seven equations, Epley and Brzycki among them, with measured one-rep maxes in untrained college students. Accuracy differed by lift, and every equation underestimated the deadlift. The result also depends on how honest the reserve is.

An estimate, not a tested max. Estimates beyond about 12 reps to failure are rough, and Epley overestimates at high reps. Test a heavy single only with a spotter or safety arms.

Sources

Epley B. Poundage chart. In: Boyd Epley Workout. Lincoln, NE: Body Enterprises, 1985.
Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. J Phys Educ Recreat Dance. 1993;64(1):88–90.
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.

Method and sources checked on October 2, 2026 by Svindland Software LLC.

Help / One-rep max

Common questions

What percentage of my max is 5 reps?

86% by Epley: the load for r reps to failure is the e1RM divided by (1 + r / 30), so 94% for 2 reps, 86% for 5 and 75% for 10. The table counts reps to failure, so a set of 5 with 2 in reserve is the 7-rep row.

Is Epley or Brzycki more accurate?

Neither is more accurate for everyone. LeSuer and colleagues compared seven equations, Epley and Brzycki among them, with measured one-rep maxes in untrained college students: accuracy differed by lift, and every equation underestimated the deadlift. From 2 to 9 reps Brzycki reads a little lower than Epley, and the two agree at 1 and at 10 reps.

Do reps in reserve count?

Yes. Reps left in reserve count as reps you could have done, so 5 reps with 2 in reserve is 7 reps to failure. An empty reserve field counts as 0, a set taken to failure, and the result depends on how honest the reserve is.

How many reps is too many for an estimate?

Estimates beyond about 12 reps to failure are rough, and Epley overestimates at high reps. The rep-max table runs to 12 reps, and Brzycki is shown only up to 10, past which its denominator shrinks quickly and its estimate climbs.