One Rep Max Calculator
Estimate your one rep max from a set of reps with the Epley and Brzycki formulas, and the weight for other rep counts.
Your set
Filled in with example values. Replace them with your own.
Results update as you type.
Result
Estimated 1RM: 114.6 kg (from 100.0 kg × 5)
Estimated one rep max
114.6kg
- Epleyweight × (1 + reps ÷ 30)
- 116.7 kg
- Brzyckiweight × 36 ÷ (37 − reps)
- 112.5 kg
Estimated weight for each number of reps
- 1 rep100%114.6 kg
- 2 reps95%109.4 kg
- 3 reps93%106.2 kg
- 4 reps90%103.1 kg
- 5 reps87%100.0 kg
- 6 reps85%97.1 kg
- 8 reps80%91.4 kg
- 10 reps75%85.9 kg
- 12 reps70%80.7 kg
How it’s calculated
Epley
100.0 × (1 + 5 ÷ 30) = 116.7 kg
Brzycki
100.0 × 36 ÷ (37 − 5) = 112.5 kg
Average
(116.7 + 112.5) ÷ 2 = 114.6 kg
How the one rep max calculator works
Your one rep max (1RM) is the most weight you could lift for a single repetition of an exercise. Enter a weight and how many clean reps you managed with it, ideally close to failure, and the calculator estimates your 1RM with the Epley and Brzycki formulas and averages them.
It then turns the formulas around to estimate the weight for other rep counts. It works the same in kilograms or pounds.
The formulas
Epley: 1RM = Weight × (1 + Reps ÷ 30)
Brzycki: 1RM = Weight × 36 ÷ (37 − Reps)
Estimate = (Epley + Brzycki) ÷ 2
A single rep is taken as the maximum itself in both.
Worked example
100 kg for 5 reps:
- Epley: 100 × (1 + 5 ÷ 30) = 116.7 kg
- Brzycki: 100 × 36 ÷ 32 = 112.5 kg
- Estimated 1RM: (116.7 + 112.5) ÷ 2 = 114.6 kg
At 10 reps both formulas agree: 60 kg for 10 reps gives an estimated 1RM of 80 kg.
Limitations
- An estimate. Results vary with the exercise, technique, experience and how close to failure the set was.
- Not a substitute for coaching. If you have an injury or a medical condition, ask a doctor or physiotherapist before heavy lifting.
Frequently asked questions
Why estimate a one rep max instead of testing it?
Lifting a true maximum is demanding and carries more risk, especially without experience or a spotter. Estimating it from a set of several reps gives a number you can plan training with, without the all-out attempt.
Why use two formulas?
Epley and Brzycki are both widely used and give slightly different answers: Epley is higher below 10 reps, they agree exactly at 10, and Brzycki is higher above. Averaging them avoids leaning on either one.
Why only up to 12 reps?
Both formulas were designed for sets of a few reps, so the estimate gets less reliable as the reps rise. The calculator stops at 12 to keep within that range.
How should I use the rep table?
It shows roughly how much you might lift for each number of reps, based on your estimated maximum. Real performance varies between exercises and people, so treat it as a starting point and adjust.