One Rep Max Calculator
Estimate the maximum weight you could lift for a single repetition without actually attempting a risky one-rep max. Enter a weight you lifted and the number of clean reps you managed, and the calculator applies the well-known Epley and Brzycki formulas to predict your one rep max, showing both because they differ slightly and give a useful range. It then builds a percentage chart of that max, since most strength programs prescribe work as a percentage of your 1RM, so you can read off suggested loads for sets of different rep ranges. Estimates are most accurate for lower rep counts, roughly ten or fewer, and drift higher than reality beyond that. Use it to program safely and track progress. Everything is computed locally in your browser.
How to use One Rep Max Calculator
- Enter the weight you lifted.
- Enter the number of reps.
- Read your estimated one rep max.
- Use the percentage chart to plan training loads.
Frequently asked questions
Which formulas does it use for 1RM?
It estimates your one rep max using both the Epley and Brzycki formulas from a weight and the reps you performed.
How accurate is an estimated 1RM?
Estimates are most reliable in the lower rep ranges, roughly under 10 reps. Higher rep sets make the estimate less precise.
What is the percentage training chart?
It lists the loads at common percentages of your 1RM, so you can plan working sets like 80 or 90 percent of your max.
What is One Rep Max Calculator?
Estimate the maximum weight you could lift for a single repetition without actually attempting a risky one-rep max. Enter a weight you lifted and the number of clean reps you managed, and the calculator applies the well-known Epley and Brzycki formulas to predict your one rep max, showing both because they differ slightly and give a useful range.
Is One Rep Max Calculator free to use?
Yes. One Rep Max Calculator is completely free, with no sign-up and no usage limits.
Does One Rep Max Calculator work in a web browser?
Yes. One Rep Max Calculator runs in any modern web browser. There is nothing to download or install.
Is my data private with One Rep Max Calculator?
Yes. One Rep Max Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.
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