Health & Fitness · Fitness
One Rep Max (1RM) Calculator — 7 Formulas and Training Loads
Estimate the most you could lift once (1RM) from a set you can do for several reps, with seven published formulas — Epley, Brzycki, Lombardi, O'Conner, Lander, Mayhew and Wathan — or their average. Get a table of training weights from 50 % to 100 % of your max and the reps you'd expect at each.
Your inputs
Quick start — try a typical case
Most accurate between 2 and 10 reps done with good form, close to failure.
Your result Live
Estimated One-Rep Max
95 kg
From 80 kg × 6 reps — average of 7 formulas
- Formula Range
- 92 kg to 97 kg
Training loads
11 rowsTest a true 1RM only with a spotter and good technique; estimates are safer for most people.
Population-average estimates for healthy adults, not medical advice. Talk to a doctor or registered dietitian before major changes to diet or exercise, or if you are pregnant or have a health condition.
How this is calculated
Epley: w(1 + r/30) · Brzycki: w × 36 ÷ (37 − r) · Lombardi: w × r^0.1 · O'Conner: w(1 + 0.025r) · Lander: 100w ÷ (101.3 − 2.67123r) · Mayhew: 100w ÷ (52.2 + 41.9e^(−0.055r)) · Wathan: 100w ÷ (48.8 + 53.8e^(−0.075r))
- w, r
- Weight lifted and reps completed
The more reps you can do with a weight, the further it is below your maximum. Each formula turns a weight-and-reps set into an estimated single-rep maximum; they agree closely for a few reps and drift apart past ten. Working at set percentages of your 1RM is how many strength programmes prescribe loads.
Assumptions & sources
- A set taken close to failure with good form; estimates are less reliable above about 10 reps.
- 1One rep max calculation formulas (Epley, Brzycki, Lombardi, O'Conner, Lander, Mayhew, Wathan) — Lumin Sports
Calculator ID HLTH-1RM-001 · version 1.0.0
Common questions
What's my max if I bench 80 kg for 6 reps?
About 96 kg by Epley (80 × 1.2) and 93 kg by Brzycki (80 × 36 ÷ 31).
Which formula is most accurate?
Brzycki and Epley are the most used; for 2–10 reps the formulas are close, so the average is a sensible choice.
How many reps at 80 % of my max?
About 8.