One Rep Max Calculator

1. Enter the weight you lifted. Use a weight you actually lifted with good form in a recent workout. Do not use a weight where you failed or used improper technique. The calculation assumes you could have done one more rep.
2. Enter the number of reps completed. The fewer reps, the more accurate the estimate. 1-5 rep tests are most accurate. Above 10 reps, endurance factors make the estimate less reliable. Best practice: use a weight you can lift 3-8 times with maximum effort.
3. Read the results. The calculator shows 5 different formula estimates and their average. Use the training percentage table below to plan sets at each intensity level.

Safety note: do not attempt actual 1RM lifts without a spotter or safety equipment. Use sub-maximal tests (3-5 rep max) and calculate your 1RM mathematically.

Epley (1985):    1RM = weight × (1 + reps/30)
Brzycki (1993):  1RM = weight × (36 / (37 - reps))
Lander (1985):   1RM = weight / (1.013 - 0.0267 × reps)
Lombardi (1989): 1RM = weight × reps^0.1
O'Conner (1989): 1RM = weight × (1 + reps/40)

Training intensity guide (based on % of 1RM):