One Rep Max Calculator
Estimate your maximum lifting strength from any rep count using proven formulas.
Results
Estimated 1RM
257.8 lbs
90% (3–4 reps)
232 lbs
80% (6–8 reps)
206.3 lbs
70% (10–12 reps)
180.5 lbs
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What is a One Rep Max Calculator?
Your one rep max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise with proper form. It is the gold standard measure of muscular strength and is used to prescribe training loads — for example, "lift 80% of your 1RM for 4 sets of 5 reps."
Testing your true 1RM requires careful warm-up, proper technique, and carries some injury risk. This calculator uses submaximal testing — you lift a weight you can handle for multiple reps, and the formula estimates your 1RM from that performance. The Epley formula (weight × (1 + reps/30)) is the most widely used.
Once you know your 1RM, you can use percentage-based programming to structure your training. Common training zones include: 90–100% for strength, 75–85% for hypertrophy (muscle growth), and 60–75% for muscular endurance.
How to Use the One Rep Max Calculator
Estimate your maximum strength without the risk of a true 1RM test.
- 1
Choose your exercise
Select the lift you want to estimate — bench press, squat, deadlift, or any other exercise.
- 2
Enter the weight lifted
Input the weight you used for your working set (in pounds or kilograms).
- 3
Enter the number of reps
Enter how many reps you completed with that weight. For best accuracy, use a set of 3–10 reps.
- 4
View your estimated 1RM
Your estimated one rep max is displayed, along with a percentage table showing recommended weights for different rep ranges.
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