One Rep Max Calculator
Estimate your 1RM from any set and get the working weights for 60–95% of it.
Inputs
Formula
- Epley: 1RM = w × (1 + reps/30)
- Brzycki: 1RM = w × 36 / (37 − reps)
Estimating a one-rep max from a set you already did is safer than testing a true max. Accuracy is best under 10 reps; beyond that fatigue distorts the estimate.
Step-by-step calculation
- 1
Epley
w(1 + r/30)
101.3 kg
- 2
Brzycki
w·36/(37−r)
99.3 kg
Frequently asked questions
What does the One Rep Max Calculator do?
Estimate your 1RM from any set and get the working weights for 60–95% of it. The One Rep Max Calculator on OneCalcApp returns the result instantly as you type, together with the formula and the substituted values.
How do I use the One Rep Max Calculator?
Enter your values in the input fields, choose the relevant units or options, and the One Rep Max Calculator recalculates automatically. You can copy, print or export the result.
Is the One Rep Max Calculator free to use?
Yes. The One Rep Max Calculator is completely free, needs no sign-up and has no usage limit on OneCalcApp.
How accurate is the One Rep Max Calculator?
It uses the standard formula Epley: 1RM = w × (1 + reps/30) and full double-precision arithmetic, so results match a manual calculation to the displayed number of digits.
Does the One Rep Max Calculator work on mobile and offline?
Yes. The One Rep Max Calculator runs entirely in your browser on phones, tablets and desktops, and your inputs never leave your device.
Where can I find related tools?
OneCalcApp hosts 300+ calculators and converters, including the full Health collection. Related tools are linked at the bottom of every page.
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