Calculate your One-Rep Max (1RM) using validated strength algorithms to establish accurate training percentages for your next macrocycle.
1RM Calculator
ONE-REP MAXIMUM
Enter a sub-maximal lift (between 1 and 10 reps) to estimate your absolute maximum strength capacity.
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Common Questions
FAQ
Why not just test my true 1RM instead of calculating it?
Testing a true 1RM places extreme stress on the central nervous system (CNS) and carries a high risk of injury if form breaks down. For 95% of athletes, calculating an estimated 1RM using a 3-5 rep max provides the exact same programming value without the injury risk or CNS fatigue.
Are these formulas accurate for 15+ reps?
No. The formulas (especially Epley and Brzycki) break down exponentially beyond 10 reps. The relationship between strength and endurance becomes too unpredictable. For the most accurate 1RM estimate, use a weight you can lift for 3 to 6 reps to failure.
Does this apply to all exercises?
Calculators are highly accurate for major compound lifts (Squat, Bench, Deadlift, Overhead Press). They are essentially useless for isolation exercises (Bicep Curls, Lateral Raises) because muscular failure in isolation movements is dictated by local muscular endurance, not systemic absolute strength.
How often should I calculate my 1RM?
You should recalculate at the beginning and end of a training block (mesocycle), typically every 4 to 8 weeks. Do not recalculate daily. Stick to the percentages based on your starting 1RM, let the weight feel easier as you get stronger, and then retest at the end of the block.