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One Rep Max (1RM) Calculator
Estimate your one-rep max from weight and reps, with training percentage breakdowns.
Free · No sign-up · Updated August 2026
Estimated one-rep max (1RM)
115 kg
Training percentages
100%
115 kg
95%
109 kg
90%
103 kg
85%
97 kg
80%
92 kg
75%
86 kg
70%
80 kg
65%
74 kg
60%
69 kg
Estimates your max using the Epley and Brzycki formulas. Most accurate for 1-10 reps. A calculated max is a guide — attempt true maxes safely with a spotter.
🔒 This tool runs entirely in your browser. Your data is never uploaded.
Frequently asked questions
How is my 1RM estimated?＋
From the weight and reps using the Epley and Brzycki formulas, averaged. It's most accurate for sets of 1-10 reps.
Should I test my true max?＋
The estimate is a safe guide. If you attempt a real 1RM, warm up thoroughly and use a spotter or safety bars.