One Rep Max Calculator
Calculate your one-rep max (1RM) for any lift using weight and reps performed.
A one-rep max calculator estimates the maximum weight you can lift for a single repetition based on the weight and reps of a submaximal set.
Examples
Bench press 185 lbs x 5 reps
Frequently Asked Questions
Which formula is most accurate?
How should I use the percentage chart?
Quick Tips
- •Test with a weight you can lift for 3-5 reps for the most accurate estimate.
- •Retest your 1RM estimate every 4-6 weeks to keep your training percentages current.
- •Track progress over weeks, not days — strength changes slowly.
A one-rep max calculator estimates the maximum weight you can lift for a single repetition based on the weight and reps of a submaximal set.
How to Use This Calculator
Enter the weight you lifted and the number of repetitions you completed. The calculator estimates your one-rep max using four proven formulas (Brzycki, Epley, Lander, Lombardi) and provides a percentage-based training chart.
Understanding the Formula
Brzycki: 1RM = W x 36/(37-R). Epley: 1RM = W x (1+R/30). Lander: 1RM = 100W/(101.3-2.67R). These are most accurate for 1-10 rep ranges.
Examples
Bench press 185 lbs x 5 reps
Brzycki: 185 x 36/32 = 208 lbs. Epley: 185 x (1 + 5/30) = 216 lbs. Average estimated 1RM: approximately 210 lbs.
Frequently Asked Questions
Which formula is most accurate?
Brzycki and Epley are the most widely validated. All formulas are most accurate in the 1-10 rep range. Above 10 reps, accuracy decreases. The average of multiple formulas gives the best estimate.
How should I use the percentage chart?
Use it to plan your training weights. For strength: work at 80-95% for 1-6 reps. For hypertrophy: 65-80% for 8-12 reps. For endurance: 50-65% for 15+ reps.
Assumptions & Limitations
- Based on population averages; individual results vary with genetics and training history.
- Accuracy decreases significantly for sets above 10 reps.
- Assumes good form was maintained throughout all repetitions.