Fuel & Forge / Free tools / One Rep Max Calculator
One Rep Max Calculator
Your one rep max (1RM) is the heaviest weight you could lift once. You don’t need to test it: a hard set of a few reps gives a good estimate, and the chart turns it into training weights.
Fill in the fields to see your result.
How it's calculated
The estimate is the average of two well-tested formulas, Epley weight × (1 + reps ÷ 30) and Brzycki weight × 36 ÷ (37 − reps). They agree closely for sets of 2 to 10 reps.
The chart shows the percentage of your 1RM and roughly how many reps most people can do at that weight. Use it to pick weights for a program.
Questions
Is it safe to test my real one rep max?
It can be, with a spotter and good warm-up, but it is rarely necessary. A hard set of 3 to 5 reps gives an estimate within a few percent, with much less risk and fatigue.
Which rep range gives the most accurate estimate?
Sets of 2 to 6 reps taken close to failure. Above 10 reps, muscular endurance varies a lot from person to person.
Does this work for every exercise?
It works best for big barbell lifts like squat, bench press and deadlift. Isolation and machine exercises are less predictable.
Let a coach do this every week
A calculator gives you a starting point. Fuel & Forge sets your calories, macros and training, then adjusts them every week from your check-ins, so you never have to recalculate.
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