This One Rep Max Calculator estimates the most weight you could lift for a single repetition, based on a set you have already done. Enter the weight and how many reps you managed, and it returns your estimated 1RM plus a full set of training percentages — no risky max attempt required. It is built for lifters programming the squat, bench press, deadlift and overhead press by percentage.
There is no single perfect equation for a one rep max, so this tool blends three well-established ones and averages the result.
E
Epley — weight × (1 + reps ÷ 30). Simple and reliable, widely used in strength training.
B
Brzycki — weight × 36 ÷ (37 − reps). Very close to Epley at low reps.
L
Lombardi — weight × reps^0.1. A power-curve approach that tempers the estimate at higher reps.
Because they are averaged, no single formula dominates your result. The full breakdown is shown under your estimate.
Reps to %1RM training guide
A standard chart of how many reps you can usually do at each percentage of your one rep max — handy for planning working sets.
Reps
% of 1RM
1
100%
2
95%
3
93%
4
90%
5
87%
6
85%
8
80%
10
75%
12
70%
15
65%
These are typical figures and vary by person and exercise — use them as a starting point, not a hard rule.
How to use it
1
Enter the weight you lifted and pick kg or lbs
2
Choose the reps you completed (or type a custom number)
3
Read your 1RM and the training percentages, then copy the result
Frequently asked questions
Your one rep max is the heaviest weight you can lift for a single repetition of an exercise with good form. It is the standard measure of maximal strength and the basis for setting training percentages.
For most people it lands within about 5–10% of a true max. It is most accurate when you base it on a set of 2–6 reps; the more reps you do, the more the estimate relies on the formula and the less precise it becomes.
The Epley and Brzycki formulas give very similar results for low reps and are the most widely used. This calculator averages Epley, Brzycki and Lombardi so no single formula skews the estimate.
Lift a challenging weight for a number of reps, then enter the weight and the reps you completed. The calculator estimates the single-rep max from that set, so you never have to attempt a true max.
Three to six reps gives the best balance of accuracy and safety. Sets above 10–12 reps still work but the estimate becomes less reliable, especially for beginners.
As a rough guide: strength is usually trained around 85–95% for low reps, muscle growth around 67–80% for moderate reps, and muscular endurance below 67% for higher reps.
Maxing out carries more injury risk, so warm up thoroughly, use a spotter or safety bars, and only attempt it once you are experienced. Estimating from a sub-maximal set is the safer option for most lifters.
Yes. Your one rep max is specific to each lift, so calculate it separately for the squat, bench press, deadlift and any other exercise you program by percentage.
Both. Pick kg or lbs before you calculate and every result, including the training percentages, is shown in the unit you chose.