What is a 1 Rep Max (1RM)?
Your 1RM is the maximum amount of weight you can lift for a single repetition with proper form. Testing a true 1RM can be dangerous without a spotter, so lifters use calculators to estimate it based on sets of higher reps (e.g., 5 or 10 reps).
The Formula
This calculator uses the Epley Formula, which is standard for compound lifts like the Bench Press, Squat, and Deadlift:
1RM = Weight × (1 + (Reps / 30))
How to use the Percentage Chart
Most training programs don't require you to lift your max every day. Instead, they ask for specific percentages:
- Hypertrophy (Muscle Growth): Usually 70-80% of 1RM for 8-12 reps.
- Strength: Usually 85-90% of 1RM for 3-5 reps.
- Power: Usually 50-60% of 1RM moved as fast as possible.