One Rep Max Calculator
Free One Rep Max Calculator using Epley and Brzycki formulas. Estimate your 1RM for bench press, squat, deadlift and get training maxes for 1-12 reps.
About This Calculator
The One Rep Max (1RM) Calculator helps you estimate the maximum weight you can lift for a single repetition of any exercise without actually testing it to failure. This is especially useful for lifters who want to track strength progress, plan training cycles, and avoid the injury risk of maximal lifts. Whether you are a powerlifter, bodybuilder, CrossFit athlete, or general fitness enthusiast, knowing your estimated 1RM lets you train at the right intensity for your goals.
Our calculator uses two scientifically validated formulas. The Epley formula (1RM = W × (1 + R/30)) was developed by Boyd Epley and is one of the most widely used prediction equations in strength training. It provides a linear estimate that works well across all rep ranges. The Brzycki formula (1RM = W × 36/(37-R)) was developed by Matt Brzycki and uses a hyperbolic curve that tends to be more accurate for lower rep ranges (1-5 reps). Both formulas are endorsed by the National Strength and Conditioning Association (NSCA).
For best accuracy, use a weight you can lift for 3-8 reps with good form. The fewer reps you perform, the more accurate the 1RM estimate becomes. Always warm up properly before testing, and use a spotter for exercises like bench press and squat. The calculator also includes a rep range chart showing estimated maxes for 1-12 reps, helping you plan your training percentages for strength (85-95% of 1RM), hypertrophy (70-85%), and endurance (50-70%) goals.
Regional Notes
India: Lifters typically use kilograms in gyms. The Epley formula is widely used in Indian powerlifting and strength sports.
United States: Many gyms use pounds. The formulas work identically with pounds — simply enter your pound weight and the results will be in pounds.
United Kingdom: Similar to India, kilograms are standard. The Brzycki formula is popular in UK strength training circles for its accuracy with lower rep ranges.
Frequently Asked Questions
What is one rep max (1RM)?
Your one rep max (1RM) is the maximum weight you can lift for a single repetition of an exercise. It's the gold standard for measuring strength and is used to calculate training loads for different rep ranges.
Which 1RM formula is most accurate?
The Epley formula (1RM = W x (1 + R/30)) works well for most exercises and rep ranges. The Brzycki formula (1RM = W x 36/(37-R)) is more accurate for lower reps (1-5). Both formulas have a margin of error of about +/-5% and are validated in strength training research.
What percentage of 1RM should I lift?
Training guidelines: 100% 1RM: 1 rep (max strength), 85-95%: 2-5 reps (strength focus), 70-85%: 6-12 reps (hypertrophy), 60-70%: 12-20 reps (muscular endurance), 50-60%: 20+ reps (warm-up and recovery).
How often should I test my 1RM?
Test your 1RM every 4-8 weeks when in a strength-focused training phase. Beginners should wait 12+ weeks before testing. Never test 1RM without proper warm-up and a spotter. Estimated 1RM from submaximal sets (3-5 reps) is safer for daily tracking.
Can I calculate 1RM for any exercise?
Yes, the Epley and Brzycki formulas work for any compound lift including bench press, squat, deadlift, and overhead press. However, different exercises recruit different muscle groups, so your actual 1RM may vary. For best accuracy, test each lift separately using weights in the 3-8 rep range.
What is the difference between Epley and Brzycki formulas?
The Epley formula (1RM = W x (1 + R/30)) is a linear model that works well across all rep ranges. The Brzycki formula (1RM = W x 36/(37-R)) uses a hyperbolic curve that tends to be more accurate for lower rep ranges (1-5 reps). Both are validated by the National Strength and Conditioning Association (NSCA) and produce similar results for moderate rep ranges.
How can I improve my one rep max?
To improve your 1RM: follow a structured strength program training at 70-95% of your 1RM, ensure proper nutrition with adequate protein intake (1.6-2.2 g per kg of body weight), get 7-9 hours of quality sleep for recovery, and allow 48-72 hours between heavy sessions for the same muscle groups. Progressive overload with small increments (2.5-5 kg) is key.