1RM Calculator
Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition with good form. It is the foundation of percentage-based strength programs and helps you set accurate training loads for every session.
StrengthBase estimates your 1RM from a submaximal set using four proven formulas — Epley, Brzycki, Lombardi, and O'Conner — so you can compare results and pick the model that fits your rep range.
Whether you train for powerlifting, bodybuilding, or general fitness, knowing your 1RM removes guesswork and makes programming measurable.
How to Use
- Enter the weight you lifted and the number of reps completed.
- Select a formula or let the tool recommend one based on your rep range.
- Read your estimated 1RM and use the intensity table to plan your next session.
Frequently Asked Questions
- What is a 1RM?
- A 1RM is the maximum weight you can lift for one full repetition. It is used to prescribe training percentages.
- Which formula is most accurate?
- Brzycki tends to be most accurate for heavy sets of 1–6 reps. Epley works well across 3–10 reps. Lombardi is better for higher rep ranges above 10.
- Do I need to test a real 1RM?
- No. A submaximal set of 3–10 reps gives a reliable estimate without the injury risk of maxing out.
- How often should I re-test?
- Re-estimate every 4–8 weeks or whenever you complete a training block to keep your percentages current.