One Rep Max Calculator
Estimate your one-rep max based on the weight lifted and number of repetitions.
Enter Your Lift
Unit
Weight Lifted
lb
Repetitions (1-12 reps for best accuracy)
reps
Formula
Your Estimated 1RM
Estimated One Rep Max
—
lb
Using Brzycki Formula
Training Zones
Compare All Formulas
What is 1RM?
One Rep Max (1RM) is the maximum weight you can lift for a single repetition with proper form. It’s a key metric for measuring strength and programming training intensity.
Calculating rather than testing your 1RM is safer and reduces injury risk while still giving you accurate training percentages.
Training Zone Guide
- 90-100% (1-3 reps): Maximal strength. Use for peaking and testing. Requires full recovery.
- 80-90% (4-6 reps): Strength building. Primary range for powerlifting programs.
- 70-80% (7-10 reps): Hypertrophy zone. Builds muscle size with moderate intensity.
- 60-70% (11-15 reps): Muscular endurance. Good for beginners and accessory work.
- 50-60% (15+ reps): Warm-up sets and technique practice.
Popular 1RM Formulas
- Brzycki: Most widely used. Accurate for 1-10 reps. Formula: Weight × (36 / (37 – reps))
- Epley: Simple and reliable. Formula: Weight × (1 + reps/30)
- Lander: Good for moderate rep ranges. Often used in research studies.
- Average: Combines all formulas for a balanced estimate.
Safety Guidelines
- Use a spotter: Always have a competent spotter when attempting heavy lifts or testing true 1RM.
- Accuracy decreases: Estimates are most accurate with 1-6 reps. 10+ reps significantly reduces accuracy.
- Don’t test often: Calculated 1RM is safer than actual 1RM attempts. Test true max only occasionally.
- Warm up properly: Progressive warm-up sets are essential before any heavy lifting.