What is one rep max (1RM)?
One rep max (1RM) is the maximum weight you can lift for a single repetition of an exercise. It is used to measure strength and plan training programs. Most strength programs are based on percentages of your 1RM.
One Rep Max Calculator
Estimate your one-rep max for strength training exercises.
This calculator provides estimates based on submaximal lifts. Actual 1RM may vary. Testing true 1RM carries injury risk. Always warm up properly, use correct form, and have a spotter when lifting heavy weights.
How to use this calculator
- Enter the requested measurements or values.
- Choose the unit system or options that match your situation.
- Review the result and interpretation.
- Use the number as an educational estimate, not a diagnosis or prescription.
Example
Use the calculator to estimate a health or fitness number, then compare it with trends over time and other relevant context.
These tools are for education and planning. They do not replace medical advice.
Frequently Asked Questions
How accurate are 1RM calculators?
These calculators provide estimates based on submaximal lifts (typically 1-12 reps). They are most accurate for 3-8 reps. Accuracy decreases with very high reps (10+) or very low reps (1-2). For best results, test with 3-5 reps.
Should I test my actual 1RM?
Testing your true 1RM carries injury risk, especially for beginners. Using a calculator with submaximal weights (3-5 reps) is safer and nearly as accurate. If you do test 1RM, warm up thoroughly and use a spotter.
How do I use my 1RM for training?
Most strength programs use percentages of 1RM. For example, 5x5 at 80% 1RM, or 3x3 at 90% 1RM. Knowing your 1RM helps you select appropriate weights for different rep ranges and training goals.