One Rep Max Calculator

Estimate the heaviest weight you could lift once from a lighter set, with seven formulas and a percentage table for programming.

Formulas last reviewed: September 2026

Enter your details

Units

Metric (kg, cm)US (lb, ft, in)

Weight lifted

Reps completed

reps

Estimates are most accurate for 1–10 reps.

Estimated one-rep max

92.4 kg

Average of 7 formulas · 80 kg × 5 reps

Epley

93.3 kg

Brzycki

90 kg

Estimate by formula

Estimate by formula
Formula	1RM
Epley	93.3 kg
Brzycki	90 kg
Lander	91 kg
Lombardi	94 kg
Mayhew	95.2 kg
O'Conner	90 kg
Wathan	93.3 kg

Training percentages

Working weight for a target rep range.

Training percentages
% of 1RM	Weight	Typical reps
100%	92.4 kg	1
95%	87.8 kg	2
90%	83.2 kg	4
85%	78.5 kg	6
80%	73.9 kg	8
75%	69.3 kg	10
70%	64.7 kg	12
65%	60.1 kg	16
60%	55.4 kg	20
55%	50.8 kg	24
50%	46.2 kg	30

Only test a true one-rep max with a spotter and a good warm-up. Estimates get less accurate for sets above 10 reps.

Disclaimer: Results are general estimates for information and education only. They are not medical advice, a diagnosis or a treatment plan. Please talk to a doctor or qualified health professional before making health, diet, exercise or pregnancy decisions.

What is a one-rep max?

Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition with good form. Coaches use it to set training loads as percentages, but testing it directly is tiring and risky.

This calculator estimates your 1RM from a lighter set of several reps, using seven well-known formulas and a table of training percentages.

How it is calculated

Epley: 1RM = weight × (1 + reps ÷ 30)

Brzycki: 1RM = weight × 36 ÷ (37 − reps)

Lander, Lombardi, Mayhew, O'Conner and Wathan use similar curves. The calculator shows all seven and their average.

Worked example

100 kg for 5 reps

Epley: 116.7 kg
Brzycki: 112.5 kg
Average of 7 formulas: 115.5 kg
80% of 1RM (about 8 reps): 92.4 kg

Using your 1RM

Strength work is often done at 70–85% of 1RM for 4–10 reps.
Estimates are most reliable for sets of 10 reps or fewer.
Warm up well and use a spotter for heavy sets.
Re-test every 4–8 weeks as you get stronger.

Frequently asked questions

Which formula is the most accurate?

They agree closely for 3 to 8 reps. Epley and Brzycki are the most popular. The average of all formulas smooths out the differences.

Why is my estimated 1RM higher than what I can lift?

Formulas assume similar strength across all rep ranges. Fatigue, technique and exercise type make real 1RMs lower or higher.

Is it safe to test a true 1RM?

Only with proper technique, warm-up and a spotter. Many people are better off using estimated 1RM from a heavy 3 to 5 rep set.

Can I use this for any lift?

Yes — squat, bench press, deadlift, overhead press and others. Accuracy is best for big compound lifts.