One Rep Max Calculator
A one-rep max is the most weight you could lift once. Testing it directly is hard and carries risk, so this estimates it from a weight you lifted for several reps.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
The Epley formula multiplies the weight by one plus the reps divided by 30. The Brzycki formula multiplies the weight by 36 and divides by 37 minus the reps.
The two formulas usually land near each other. Both are most reliable for sets of about ten reps or fewer.
Worked example
Lifting 185 lb for 5 reps suggests a one-rep max of about 215.8 lb by one formula and 208.1 lb by the other.
Questions
Should I test my real one-rep max?
A true max lift carries injury risk, and a qualified trainer can help you do it safely.
Which reps give the best estimate?
Sets of about five to ten reps are common inputs. Very high reps make the estimate less reliable.
Does this work for every exercise?
It works best for barbell lifts done with good form. Machines and body-weight moves can read differently.
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