One Rep Max Calculator
Estimate your 1RM from any set with seven formulas, a percentage table and plate loading.
How to use the One Rep Max Calculator
- 1Enter the weight you lifted and how many reps you did.
- 2Choose kilograms or pounds and the formula for the table.
- 3Read your 1RM, the training percentages and how to load the bar.
About One Rep Max Calculator
The One Rep Max Calculator estimates the most weight you could lift for a single repetition from a set of up to 20 reps, without testing a true maximum. It calculates your 1RM with seven established formulas, Epley, Brzycki, Lombardi, Mayhew, O'Conner, Wathen and Lander, shows each result and their average, and works in kilograms or pounds.
A training table lists the weights from 50 to 100 percent of your 1RM, rounded to the jump your plates allow, with an estimate of how many reps you can do at each. You can base the table on the average or on one formula. Select any row and the calculator shows how to load the bar: which plates go on each side for a 20, 15 or 10 kg bar or a 45, 35 or 15 lb bar, with a simple picture of the loaded barbell.
Strength athletes, powerlifters and coaches use it to set training weights for programs written in percentages of 1RM, to track progress without risky max attempts, and to plan warm-up sets. For cardio training intensity, see the Heart Rate Zone Calculator.
Frequently asked questions
How is one rep max calculated?
The Epley formula is the most common: 1RM = weight × (1 + reps ÷ 30). 100 kg for 5 reps gives 100 × (1 + 5 ÷ 30) = 116.7 kg. Brzycki uses weight × 36 ÷ (37 − reps), which gives 112.5 kg for the same set.
Which 1RM formula is the most accurate?
No formula fits everyone. Epley and Brzycki are the most widely used and agree closely up to about 10 reps; averaging several formulas smooths out their differences.
How many reps should I use for the estimate?
Sets of 3 to 10 reps taken close to failure give the best estimates. Above 10 to 12 reps, muscular endurance plays a bigger role and the formulas drift apart.
How many reps can I do at 80% of my max?
About 8. Typical values are 2 to 3 reps at 95 percent, 4 to 5 at 90 percent, 8 at 80 percent and 10 at 75 percent, though they vary between lifters and exercises.
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