Free tool
One rep max calculator
Estimate your 1RM from any set. Enter the weight you lifted and how many reps you got, and see your max plus a full training percentage table.
How it works
Your one rep max (1RM) is the heaviest weight you could lift for a single rep with good form. You do not need to test it in the gym: a heavy set of 2 to 10 reps predicts it well.
This calculator averages the two most used formulas, Epley and Brzycki. Estimates are most accurate below 10 reps. Use the percentage table to plan training weights: for example, 5 reps at around 85 percent of your 1RM.
Common questions
How accurate is a 1RM calculator?
Within a few percent for sets of 2 to 10 reps. Above 10 reps the estimate gets less reliable because fatigue, not strength, starts to limit the set.
Which formula does this calculator use?
It shows the average of the Epley formula (weight x (1 + reps / 30)) and the Brzycki formula (weight x 36 / (37 - reps)), the two most widely used equations.
Should beginners test a real 1RM?
Usually no. An estimated 1RM from a heavy set of 3 to 5 reps is safer and accurate enough to plan training percentages.
How do coaches use 1RM in programming?
Training blocks are usually written as percentages of 1RM: for example 5x5 at 80 percent. Coaches on ProCoach track every client's lifts and personal records automatically inside the app.
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