What is the Wathan Formula?
Formula
1RM = (100 × Weight) ÷ (48.8 + 53.8 × e^(-0.075 × Reps))
The Wathan formula was developed by D.G. Wathan and is based on extensive research data. It uses an exponential decay function to model the relationship between reps and 1RM.
Example Calculation:
If you can deadlift 315 lbs for 5 reps:
1RM = (100 × 315) ÷ (48.8 + 53.8 × e^(-0.075 × 5))
1RM = 31500 ÷ (48.8 + 53.8 × e^(-0.375))
1RM = 31500 ÷ (48.8 + 53.8 × 0.6869)
1RM = 31500 ÷ (48.8 + 36.9)
1RM = 31500 ÷ 85.7
1RM = 367.4 lbs (166.7 kg)
1RM = 31500 ÷ (48.8 + 53.8 × e^(-0.375))
1RM = 31500 ÷ (48.8 + 53.8 × 0.6869)
1RM = 31500 ÷ (48.8 + 36.9)
1RM = 31500 ÷ 85.7
1RM = 367.4 lbs (166.7 kg)
Why Use Wathan?
- Research-based: Developed from extensive studies
- Exponential model: Accounts for non-linear fatigue
- Scientific approach: Uses mathematical modeling
- Consistent results: Reliable across rep ranges