One Rep Max Calculator
Your one-rep max (1RM) is the maximum weight you can lift for a single repetition. Knowing your 1RM helps you plan training percentages, track strength progress, and programme exercises effectively. Our calculator uses three validated formulas to estimate your 1RM without needing to test it directly — which is safer and more practical.
About this calculator
This calculator uses three well-known formulas (Epley, Brzycki, and Lombardi) to estimate your one-rep max. These formulas are most accurate when using sets of 2-6 reps. Accuracy decreases with higher rep counts. Never attempt a true 1RM without a spotter and proper warm-up. Results are estimates and should be used as a training guide, not a guarantee.
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Frequently Asked Questions
What is a one rep max (1RM)?
How accurate are 1RM calculator formulas?
Which 1RM formula is the best?
How should I use my 1RM for training?
How often should I test or recalculate my 1RM?
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