What is a one-rep max (1RM)?
Your one-rep max is the heaviest weight you can lift once with good form in an exercise. Many strength programs prescribe loads as a percentage of it («5 sets of 5 at 80%»), so knowing it lets you plan your training.
Testing a true 1RM carries some injury risk and needs a proper warm-up and a spotter. That is why it is usually estimated from a set of several reps with the Epley, Brzycki or Lombardi formulas.
Example · bench press, 185 lb × 6 reps
Epley: 185 × (1 + 6/30) = 222 lb. Brzycki: 185 × 36 / 31 = 214.8 lb. Lombardi: 185 × 60.1 = 221.3 lb. Average: 219.4 lb. To train at 80% you would use about 175 lb.
How to use the percentage table
- 90–100% (1–4 reps): max strength.
- 80–90% (4–8 reps): strength.
- 67–80% (8–12 reps): hypertrophy (muscle growth).
- Below 67% (12+ reps): muscular endurance and technique.
Frequently asked questions
Which formula is the most accurate?
They are all close between 2 and 8 reps. Epley tends to give slightly higher values and Brzycki slightly lower ones at high reps, which is why the calculator shows the average.
Does it work for every exercise?
It works best for compound barbell lifts (squat, bench press, deadlift, overhead press). For machines or isolation exercises the estimate is less reliable.
What about nutrition?
Work out your calories and macros for your goal with the macro calculator.