Tools · One rep max calculator

One rep max calculator: estimate your 1RM from any set

No need to max out. Enter a set you took to failure, or close to it, and get an estimate of the most you could lift once.

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Your set

Units

Weight liftedlb

Reps

Your result≈ 258 lb

Your result

≈ 258 lbFrom 225 lb × 5 reps

Epley: 263 lb
Brzycki: 253 lb

Training loads

% of max	Weight
95%	245 lb
90%	230 lb
85%	220 lb
80%	205 lb
75%	195 lb
70%	180 lb
65%	170 lb
60%	155 lb
50%	130 lb

How many reps you can do at each percentage varies by person and by lift.

An estimate, not a test result. Warm up, and use a spotter or safety bars for heavy sets.

≈258 lb estimated max. CaloLift logs every set, so you can watch it go up.

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How it is calculated

Brzycki (1993): 1RM = weight ÷ (1.0278 − 0.0278 × reps). Matt Brzycki, a strength coach at Princeton, built it from the almost linear link between reps to fatigue and the share of a maximal load.
Epley (1985): 1RM = weight × (1 + reps ÷ 30), from Boyd Epley's poundage chart.
The result is the average of the two. With a single rep, your max is simply the weight you lifted.

Getting a good estimate

Use a set taken to failure, or within a rep of it, with good form. A set you stopped early gives a low estimate.
Sets of 3–10 reps work best. Brzycki notes that his formula becomes less accurate above about 10 reps.
The same percentage gives different reps on different lifts and for different people. A 2024 meta-regression (Nuzzo et al.) estimated about 4, 9 and 14 reps on the bench press at 90%, 80% and 70% of 1RM, and noticeably more on the leg press.

Using the training loads

The table shows each percentage of your estimated max, rounded to 2.5 kg or 5 lb so you can load the bar. Many programs set the work as a percentage of 1RM. A rough guide from Brzycki: about 75% of your max is a weight you can lift around 10 times.

Compare your numbers with your own past results, not with other people's. Brzycki makes the same point: strength potential differs from one person to the next.

A reminder

These are estimates for healthy adults, not a test result or medical advice. Heavy lifting carries a risk of injury: warm up, use a spotter or safety bars, and stop if something hurts.

Quick answers

How do I calculate my one rep max?

Lift a weight for as many good reps as you can, then use a formula. With Brzycki, divide the weight by 1.0278 − 0.0278 × reps. With Epley, multiply it by 1 + reps ÷ 30. This calculator averages the two.

How accurate is a 1RM calculator?

It is an estimate. Brzycki notes that accuracy drops above about 10 reps, and the US military's Human Performance Resources (HPRC) says multiple-rep tests for lifts like the back squat are not very reliable above 5 reps, because form breaks down quickly.

Is estimating safer than testing a true max?

Usually. Brzycki argues that a reps-to-fatigue test is much safer than a 1RM lift because it uses lighter loads. Warm up and use a spotter either way.

Sources

Brzycki (1993), Strength testing: predicting a one-rep max from reps-to-fatigue, JOPERD 64(1):88–90
Epley (1985), poundage chart, Boyd Epley Workout (Lincoln, NE)
Nuzzo et al. (2024), Maximal number of repetitions at percentages of the one repetition maximum: a meta-regression, Sports Med 54:303–321
HPRC (Human Performance Resources by CHAMP): What is a one-rep max?

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