One Rep Max (1RM) is the maximum weight you can lift for a single repetition with proper form. Its used to measure strength and plan training programs. This calculator estimates 1RM using multiple proven formulas.

• 1RM is used as an absolute indicator of strength
• It can be estimated without actual 1RM testing
• Training weights are set as a percentage of 1RM

1. Enter the weight you lifted. 2. Enter the number of repetitions (up to 10 recommended for accuracy). 3. View estimated 1RM from different formulas. 4. Use the training percentages chart to plan your workouts.

1. Do not test with weights you can lift more than 10 times
2. Weights that can be lifted 1-10 times are most accurate
3. Compare results from multiple formulas for reference

Epley and Brzycki formulas are most commonly used. Lander, Lombardi, and OConner provide additional reference points. Each formula has different strengths depending on rep range and individual variation.

• Brzycki: 1RM = W × (36 / (37 - R))
• Epley: 1RM = W × (1 + R/30)
• Lander: 1RM = 100 × W / (101.3 - 2.67123 × R)
• Lombardi: 1RM = W × R^0.1
• O'Conner: 1RM = W × (1 + R/40)