1RM CALCULATOR
Estimate your One Rep Max (1RM) from any submaximal lift. 6 widely-used formulas, one percentage table — also known as ORM, one-rep max, or rep max estimator.
How do 1RM formulas work? Read the guide →
| % of 1RM | Weight | Estimated Reps |
|---|
How to Calculate Your 1 Rep Max (1RM)
Your One Rep Max (1RM) is the maximum weight you can lift for a single clean repetition. It's the baseline for every percentage-based program — 5/3/1 Wendler, Smolov Jr., Russian Squat Cycle all scale from your 1RM.
It can also be a competition benchmark: in fixed-format events like XENOM, "The Decathlon of Fitness", the opening event is a 1RM snatch. See how XENOM compares to Hyrox and CrossFit →
Instead of testing a true max (risky, and only accurate on the day), this calculator estimates it from a submaximal set using six widely-used formulas (Epley, Brzycki, Lombardi, Mayhew, O'Conner, Wathen). Accuracy is highest at 1–5 reps; above 10 reps the estimate becomes unreliable.
Once you know your 1RM, the percentage table turns it into working weights for any set scheme. As a quick percentage-of-1RM-by-reps reference: 100% for 1 rep, 95% for 1–2 reps, 90% for 3–4, 85% for 5–6, 80% for 7–8, 75% for 9–10, 70% for 11–12, 65% for 13–15, and 60% for 16–20 reps.
1 Rep Max Calculator FAQ
Which 1RM formula is most accurate?
No single 1RM formula is universally most accurate. Epley and Brzycki are two of the most commonly used simple formulas, and this calculator averages six widely used formulas (Epley, Brzycki, Lombardi, Mayhew, O'Conner, Wathen) to smooth out individual formula bias. For the best estimate, use 1–5 reps.
How many reps should I use?
Use 1 to 5 reps. A heavy set of 3 or 5 gives the best balance of safety and precision. Accuracy drops significantly above 10 reps — the formulas weren't built for endurance ranges.
What's the difference between 1RM and Training Max?
Your 1 Rep Max (1RM) is your true maximum. A Training Max (used in 5/3/1 Wendler and similar programs) is set intentionally lower — typically 85–90% of your 1RM — to keep working sets sustainable and allow progression cycle after cycle.
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