One Rep Max Calculator
Calculate your maximum strength potential using scientifically-validated formulas. Get training percentages and progression recommendations for optimal muscle building and power development.
Calculate Your 1RM
Calculation Formulas
Epley Formula
Weight × (1 + reps/30)
Good for 1-10 reps
McGlothin Formula
Weight × (1 + reps/30)
Similar to Epley
Lombardi Formula
Weight × reps^0.10
Best for higher reps
O'Conner Formula
Weight × (1 + reps/40)
Good accuracy range
Wathen Formula
Weight × (48.8 + (53.8 × e^(-0.075 × reps))) / (48.8 + 53.8)
Advanced calculation
Important Notes
1RM calculations are estimates. Actual maximum strength may vary based on technique, fatigue, and equipment. Always prioritize proper form and consider working with a qualified trainer for heavy lifts.
Understanding 1RM & Training Percentages
Why Calculate 1RM?
- • Determine training loads for different goals
- • Track strength progress over time
- • Program periodization effectively
- • Set realistic strength targets
Training Zone Applications
- • 90-100%: Strength & power development
- • 80-85%: Hypertrophy & strength building
- • 60-75%: Muscular endurance & beginners
- • 50-60%: General conditioning