One Rep Max Calculator
Calculate your estimated one rep max (1RM) for any lift using proven formulas like Epley and Brzycki. Get percentage-based training weights and rep ranges for effective strength programming.
âš Always use a spotter when attempting max lifts
For training guidance only. Listen to your body and prioritize safety.
All calculations happen in your browser. No data is sent to any server.
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How to Use
- 1 Enter weight lifted — Input the weight you lifted and select your preferred unit (lbs or kg).
- 2 Enter reps completed — Enter how many repetitions you completed with that weight. For best accuracy, use 1-10 reps.
- 3 Select formula — Choose a calculation formula. Epley is the default and most commonly used. You'll see results from all formulas for comparison.
- 4 View your estimated 1RM — See your calculated one rep max based on your inputs.
- 5 Use training percentages — Reference the training table to find appropriate weights for different rep ranges and training goals like strength, hypertrophy, or endurance.
Frequently Asked Questions
What is a one rep max (1RM)?
Your one rep max (1RM) is the maximum weight you can lift for a single repetition with proper form. It's a key metric in strength training used to calculate training percentages, design workout programs, and track progress over time. Knowing your 1RM helps you train at the right intensity for your goals.
Which formula is most accurate?
The Epley and Brzycki formulas are most widely used and tend to be accurate for 1-10 rep ranges. For higher rep ranges (10+), accuracy decreases for all formulas. The calculator shows results from multiple formulas so you can compare. Your actual 1RM may vary based on factors like fatigue, technique, and exercise selection.
How do I use the training percentages?
Different percentages target different goals: 90-100% for maximum strength (1-3 reps), 80-90% for strength/power (4-6 reps), 65-80% for hypertrophy/muscle building (8-12 reps), and 50-65% for muscular endurance (15+ reps). Use the training table to find appropriate weights for your specific goals.
Should I test my actual 1RM?
Testing a true 1RM carries injury risk and requires proper warm-up, experienced spotters, and good technique. For most people, using calculated estimates from submaximal lifts (like 3-5 reps) is safer and more practical. Only test actual 1RM if you're experienced, have proper supervision, and are competing or need precise numbers for programming.