One Rep Max Calculator
Estimate the maximum weight you could lift for a single rep, based on a set you've already done — without risking a true max attempt.
Show solution steps
What is the One Rep Max Calculator?
Your one-rep max (1RM) is the most weight you can lift once with good form. It's the reference point for programming strength training as a percentage of your max.
How to Calculate
The Epley formula: 1RM = weight × (1 + reps ÷ 30). This calculator also shows the Brzycki estimate and useful working percentages.
Formula
1RM = weight × (1 + reps ÷ 30)
How to Use
- Enter your details in the fields above.
- The result updates instantly as you type.
- Use Copy, Print or Download PDF to save your result.
Frequently Asked Questions
How accurate is this?
Estimates are most accurate for sets of 10 reps or fewer. Beyond that, form and fatigue make them less reliable.
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