One Rep Max (1RM) Calculator
Estimated 1RM (average)
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Epley formula
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Brzycki formula
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Lombardi formula
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About This Calculator
Your one-rep max (1RM) is the maximum weight you can lift for a single repetition of a given exercise. This calculator estimates your 1RM from the weight and number of reps you can perform, using three well-known formulas: Epley, Brzycki, and Lombardi. The averaged result gives a balanced estimate. These predictions are most accurate when you enter a weight you can lift for 2 to 10 reps; accuracy decreases for sets above 15 reps. The percentage table helps you plan training loads for strength, hypertrophy, and endurance goals. Always train with a spotter when attempting heavy lifts, and treat these numbers as guidelines rather than absolute targets.
FAQ
What is a one-rep max?
A one-rep max (1RM) is the heaviest weight you can lift for exactly one full repetition with proper form. It is used to gauge overall strength and to program training loads as percentages of that maximum.
Which formula is most accurate?
The Brzycki formula tends to be more accurate for low rep ranges (2-6 reps), while the Epley formula performs better for moderate rep ranges (7-10 reps). Lombardi offers a middle ground. The average of all three provides the most balanced estimate.
Is testing your actual 1RM safe?
Testing a true 1RM carries higher injury risk than regular training. If you choose to test, always warm up thoroughly, use a spotter, and ensure proper form. For most people, estimating from a submaximal set is safer and nearly as useful.
How do I use 1RM percentages for training?
Training programs assign loads based on 1RM percentages. For example, 80-85% for strength work (5-6 reps), 65-75% for hypertrophy (8-12 reps), and 50-65% for muscular endurance (15+ reps). The percentage table above calculates these weights for you automatically.