One Rep Max (1RM) Calculator
Free one rep max calculator: estimate your 1RM from a weight and the reps you did with the Epley, Brzycki and Lombardi formulas, plus a load table by reps.
| Reps | % of 1RM | Load |
|---|
What it does
Your one rep max (1RM) is the heaviest weight you can lift once with good form. Testing it directly is tiring and risky, so it is usually estimated from a lighter set taken close to failure. This calculator applies the Epley, Brzycki and Lombardi formulas, shows their average and builds a table with the load for each number of repetitions, which helps plan training percentages.
How to use it
- Choose kg or lb and type the weight you lifted.
- Type how many repetitions you did with good form, ideally 3 to 10.
- Use the table to choose the load for your next sets.
These are estimates for healthy adults and do not replace advice from a doctor, dietitian or coach. The calculation runs in your browser.
Frequently asked questions
Which formula should I trust?
They agree closely for 3 to 8 repetitions and drift apart above 10. The average smooths the differences; for one lift, the formula that matched your last real test is the best guide.
How do I use percentages of 1RM?
Strength work usually uses 80% to 90% for few reps, muscle growth about 65% to 85% for 6 to 15 reps, and endurance lighter loads. The table shows the load matching each repetition count.
Is it the same for every exercise?
It works best for big multi-joint lifts such as squat, bench press and deadlift. For machines and small exercises the estimate is less reliable.
Should I test a real 1RM?
Only with experience, a good warm-up and a spotter. For most people an estimate from a set of 3 to 5 reps is accurate enough and much safer.
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