One Rep Max Calculator

Estimate the most weight you could lift for a single rep without having to test it. Enter the weight and the number of reps you did in a set to get your one-rep max and your training loads.

Estimated one-rep max

257.8 lb

Epley formula: 262.5 lb
Brzycki formula: 253.1 lb

Training loads

% of 1RM	Weight
100%	257.8 lb
95%	244.9 lb
90%	232.0 lb
85%	219.1 lb
80%	206.3 lb
75%	193.4 lb
70%	180.5 lb
65%	167.6 lb
60%	154.7 lb
55%	141.8 lb
50%	128.9 lb

Results are estimates for information only and do not constitute financial, medical, or legal advice.

How the estimate works

The more reps you can do with a weight, the further that weight is from your maximum. Formulas like Epley's and Brzycki's turn a set of several reps into an estimated one-rep max (1RM). The calculator shows both and uses their average as the main estimate. The result is general information and not a training or medical recommendation.

The formulas

Epley: 1RM = weight × (1 + reps ÷ 30)

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

Worked example

You bench press 100 kg for 5 reps.

Epley: 100 × (1 + 5 ÷ 30) = 100 × 1.1667 = 116.7 kg.
Brzycki: 100 × 36 ÷ (37 − 5) = 3,600 ÷ 32 = 112.5 kg.
Estimate: (116.7 + 112.5) ÷ 2 = 114.6 kg, so 75% of your 1RM is about 85.9 kg.

Frequently asked questions

How accurate is a one-rep max estimate?

It is a good guide, especially with sets of 2 to 6 reps. With more reps the formulas drift apart and the estimate becomes less reliable, which is why the calculator accepts up to 12.

Should I test my real one-rep max?

Lifting your true maximum carries more risk, so many people use an estimate instead. If you do test it, warm up properly, use good form, and have a spotter or safety bars.

What do I use the percentage table for?

Many training programs give loads as a percentage of your 1RM, such as 3 sets at 75%. The table shows the weight for each percentage based on your estimate.

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