About this tool
A one rep max calculator (1RM calculator, max weight calculator) estimates the heaviest weight you could lift once from a lighter set done for several reps, so you do not have to attempt a risky max.
Epley: 1RM = weight x (1 + reps / 30). Brzycki: 1RM = weight x 36 / (37 - reps). For example, 80 kg for 5 reps gives 93.3 kg by Epley and 90.0 kg by Brzycki, and the tool averages them to about 91.7 kg.
It then lists 90, 80, 70 and 60 percent of that number, which many lifters use to plan sets. What is a good rep range to use?
Estimates are steadier with 2 to 10 reps; this tool accepts 1 to 20 reps, but above about 10 reps the guess gets rougher. Can I use it for bench press, squat and deadlift?
You can for any lift, but form, fatigue, and warm-up change the result, so the numbers are a rough guide.
Do not test a true max without a spotter, proper warm-up and good technique; you are responsible for your own safety, and a coach or doctor can advise on your training.
For calories burned during workouts, see the exercise calorie calculator. All calculations stay in your browser and nothing is saved or sent.
How to use
- Enter the weight you lifted in kg.
- Enter how many clean reps you did, from 1 to 20.
- Read the estimated 1RM by Epley, Brzycki and their average.
- Use the percentage rows to plan sets, and never test a true max without a spotter.