Fitness

One rep max calculator

Estimate your 1RM from a sub-max set using the Epley formula. Includes a full loading percentage table.

Weight lifted

Reps performed

Best accuracy at 2–10 reps

Estimated 1RM

—

Epley formula: 1RM = weight × (1 + reps ÷ 30).

100% private. All processing happens locally in your browser — no files or data are ever sent to a server.

How to use One rep max calculator

01 Fill in the required values using the fields provided
02 Results calculate automatically as you type
03 Copy or note the result — all calculations stay on your device

Frequently asked questions

Common questions about One rep max calculator.

Is One rep max calculator free to use?

Yes, One rep max calculator is completely free. No account, subscription, or payment is ever required — just open the page and start using it.

Does One rep max calculator upload my data to a server?

No. One rep max calculator runs entirely in your web browser using client-side JavaScript. Your files, text, and data never leave your device, making it 100% private.

Can I use One rep max calculator on my phone or tablet?

Yes. One rep max calculator is fully responsive and works on all modern smartphones, tablets, and desktop browsers without installing any app.

Are these results accurate enough to rely on?

One rep max calculator uses well-established formulas and provides accurate estimates for everyday use. For financial, medical, or legal decisions, always consult a qualified professional.

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About One rep max calculator

Your one-rep max (1RM) is the maximum weight you can lift for a single complete repetition with proper form — the standard benchmark for absolute strength in powerlifting and resistance training. Direct 1RM testing is taxing and carries injury risk. The One Rep Max Calculator estimates your 1RM from a sub-maximal set using the Epley formula (weight × (1 + reps ÷ 30)), one of the most widely validated prediction equations. It also generates a loading percentage table showing recommended weights for different training intensities from 65% to 100% of 1RM, which is the foundation of most evidence-based strength programming.