One-Rep Max Calculator
Estimate your one-rep max for any lift using the Epley, Brzycki, and Lombardi formulas.
100% client-side · no upload
Epley (most common)
Brzycki
Lombardi
How to use
- Enter the weight you lifted in kilograms.
- Enter the number of reps you completed with that weight (best accuracy at 2–10 reps).
- Results update instantly — see your estimated 1RM from three formulas.
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More ways to use this tool
Frequently Asked Questions
- Is this 1RM calculator free?
- Yes, completely free with no signup and no usage limits.
- Does my data leave my device?
- No. All calculations run in JavaScript inside your browser. Nothing is sent to any server.
- Does it work on mobile?
- Yes. The calculator is mobile-first and works on iPhone Safari and Android Chrome.
- Which formula is most accurate?
- Epley is most widely cited and reliable for 2–10 reps. Brzycki tends to be more accurate at lower rep counts (2–6). Lombardi may underestimate at higher reps. Treat all three as estimates — actual 1RM may vary.
- Why show three formulas?
- Different coaches and programmes reference different formulas, and outputs can vary by 5–10%. Showing all three lets you see the range and pick the formula your programme uses.
Last updated: By jarvisbox