Calculator Inputs
kg/lb
reps
Results
116.7
Estimated 1RMkg/lb
About This Calculator
Your One-Rep Max (1RM) is the maximum weight you can lift for a single repetition. Most people estimate it from a heavier sub-max set using the Epley formula.
Epley Formula
1RM = weight × (1 + reps ÷ 30)
So 100 kg for 5 reps ≈ 100 × (1 + 5/30) = 116.7 kg estimated 1RM. Use the percentage table to plan training loads (e.g. 80% for strength sets).
110.8
95%
105.0
90%
99.2
85%
93.3
80%
87.5
75%
81.7
70%
75.8
65%
70.0
60%
Frequently Asked Questions
How accurate is the Epley formula?
Epley is accurate for sets of 1–10 reps. Beyond that it over-estimates. For very low reps (1–3) the Brzycki formula can be slightly closer.
Should I test my true 1RM?
Not often. True 1RM testing is taxing and risky. Estimate from sub-max sets most of the time and test a real 1RM only every few months.