One Rep Max Calculator
Estimate your 1RM using multiple strength formulas
Estimated 1RM (average)
260.2 lbs
Formula breakdown
Epley262.5 lbs
Brzycki253.1 lbs
Lombardi264.3 lbs
Mayhew267.8 lbs
O'Conner253.1 lbs
Percentage table (based on average 1RM)
100%
260.2
95%
247.2
90%
234.1
85%
221.1
80%
208.1
75%
195.1
70%
182.1
65%
169.1
60%
156.1
55%
143.1
50%
130.1
How one rep max is estimated
A one-repetition maximum (1RM) is the heaviest weight you can lift for exactly one repetition. Since testing true 1RM is risky, strength coaches use submaximal formulas: lift a weight you can handle for 2–10 reps, then estimate 1RM mathematically. This tool averages five formulas — Epley, Brzycki, Lombardi, Mayhew, and O'Conner — for a balanced estimate. The percentage table shows training loads: 80% is the standard hypertrophy range (8–12 reps), 85–90% is strength, and 95–100% is peaking. Best accuracy is achieved with 2–5 rep sets.
Private & free — this tool runs entirely in your browser.
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