One Rep Max Calculator

Modify the values and click the Calculate button to use

One Rep Max: 116.7 kg

Estimated 1RM: 116.7 kg
Formula: Epley

One-rep max estimates are most useful when the test set is 1–10 reps and performed with good technique. Warm up thoroughly and use a spotter for maximal lifts.

Estimated max reps

Reps	Weight	% of 1RM
1	116.7 kg	100%
2	109.4 kg	94%
3	106.1 kg	91%
4	102.9 kg	88%
5	100.0 kg	86%
6	97.2 kg	83%
7	94.6 kg	81%
8	92.1 kg	79%
9	89.7 kg	77%
10	87.5 kg	75%

What this one-rep max calculator does

Your one-rep max (1RM) is the heaviest weight you can lift once with good technique. Testing a true 1RM is demanding and carries some risk, so lifters often estimate it from a set of several repetitions. This calculator uses three common formulas — Epley, Brzycki, and Lombardi — and shows the estimated weight for 1 to 10 repetitions.

Estimates are most useful when the test set is between 1 and 10 reps and performed with consistent technique.

How to use this calculator

Enter the weight you lifted.
Enter the number of repetitions completed.
Choose a formula.
Choose kilograms or pounds.
Click Calculate to see your estimated 1RM and the rep table.

The default example is 100 kg lifted for 5 reps with the Epley formula.

One-rep max formulas

Epley:    1RM = weight × (1 + reps ÷ 30)
Brzycki:  1RM = weight × 36 ÷ (37 − reps)
Lombardi: 1RM = weight × reps ^ 0.10

If you enter 1 rep, the calculator treats the lifted weight as the 1RM.

What the results mean

Estimated 1RM: the heaviest weight you could lift once, according to the selected formula.
Rep table: estimated weight for 1–10 reps and its percentage of the estimated 1RM.
Formula: the equation used. Different formulas can differ by several percent.

The default Epley estimate is 116.7 kg. The table shows about 109.4 kg for 2 reps (94% of 1RM) and 100.0 kg for 5 reps (86%).

Assumptions and limitations

The formulas assume a trained lifter, a consistent tempo, and a set taken close to failure. They are less accurate for high-repetition sets, beginners, or exercises where technique breaks down. They do not account for fatigue, training status, or the specific lift.

Do not attempt a true 1RM without a warm-up, a spotter, and safe equipment. The calculator is not a substitute for coaching or medical advice.

Frequently asked questions

Which formula is most accurate?

There is no universal winner. Epley is common and simple; Brzycki tends to give lower estimates at higher reps; Lombardi uses a power curve. Compare the range rather than trusting one number.

Can I estimate 1RM from a 20-rep set?

The formulas become less reliable above about 10–12 reps. Use a set closer to 3–8 reps for a better estimate.

Does the rep table tell me what I can lift?

It is an estimate based on the selected formula. Your actual performance depends on technique, fatigue, and the exercise.

Is testing a 1RM safe?

Not for everyone. Use a spotter, warm up properly, and use safety pins or a rack. If you are new to lifting or have a medical condition, ask a qualified coach or clinician.

Reference table

Repetition percentage chart

Repetitions	Weight	% of 1RM
1	1RM	100%
2	95% of 1RM	95%
3	93% of 1RM	93%
5	87% of 1RM	87%
8	80% of 1RM	80%
10	75% of 1RM	75%
12	70% of 1RM	70%
15	65% of 1RM	65%

Percentages are estimates. Individual strength-endurance profiles vary; use the chart as a starting point, not a prescription.

Source

References:

Disclaimer

This calculator is for informational and educational purposes only. It is not coaching or medical advice. Maximal lifting carries risk. Train within your ability and use qualified supervision.

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