What is a 1RM? Your "one-rep max" (1RM) is the maximum amount of weight you can lift for exactly one full repetition of any exercise. It is the universal benchmark for measuring absolute strength. Rather than exhausting yourself with a dangerous all-out attempt, this tool estimates your 1RM safely from a weight you already know you can lift for multiple reps.
The load you used for your set
How many reps you completed
Heads-up: Formulas become less accurate above 10 reps because fatigue and muscular endurance play a larger role than raw strength, skewing the estimate. For best results, use a set of 1 to 10 reps.
Your Estimated 1 Rep Max
--lbs
Average of Epley and Brzycki formulas
Epley: --
Brzycki: --
Training Percentages and Zones
| % of 1RM | Weight |
|---|
Zone Guide
90 - 100%
Max Strength / Testing
Very heavy, 1 to 3 reps. Builds peak neuromuscular strength. Use sparingly to avoid injury.
85 - 90%
Strength
Heavy singles, doubles, and triples. Classic powerlifting and strength-sport territory.
75 - 85%
Strength and Hypertrophy
4 to 8 reps per set. Builds both size and strength. A popular "sweet spot" for most lifters.
65 - 75%
Hypertrophy (Muscle Growth)
8 to 15 reps per set. The classic bodybuilding range for maximizing muscle size.
Below 65%
Endurance and Warm-ups
15+ reps. Great for muscular endurance, active recovery, technique practice, and warm-up sets.
Important: This is a mathematical estimate, not a guaranteed number. Actual 1RM performance varies based on your technique, fatigue level, equipment, exercise selection, and individual physiology. Never attempt a true max lift without a trained spotter and proper warm-up. Always prioritize safety over numbers.