What is one rep max (1RM)?

One rep max is the maximum weight you can lift for a single repetition with proper form. It is the standard measure of maximal strength and is used to program training percentages.

How is 1RM calculated?

Our calculator uses the Epley formula: 1RM = weight × (1 + reps / 30). For example, if you bench press 80 kg for 8 reps, your estimated 1RM is 80 × (1 + 8/30) = 101.3 kg.

One Rep Max Calculator | Fitness Calculators

One Rep Max Calculator

Your Result

Enter your data and press Calculate

Understanding One Rep Max

Your one rep max (1RM) is the heaviest weight you can lift for a single repetition of a given exercise. It serves as the foundation for strength training programming, allowing you to calculate appropriate working weights for different rep ranges and training goals.

The Epley Formula

Our calculator uses the Epley formula (1985), one of the most widely used and validated 1RM prediction equations. It works best with rep counts between 1 and 10.

Real-World Examples

Bench press 100 kg for 5 reps: Estimated 1RM = 100 × (1 + 5/30) = 116.7 kg.
Squat 120 kg for 8 reps: Estimated 1RM = 120 × (1 + 8/30) = 152.0 kg.
Deadlift 140 kg for 3 reps: Estimated 1RM = 140 × (1 + 3/30) = 154.0 kg.

Using Your 1RM for Training

Common training percentages: strength work at 85-95% of 1RM (1-5 reps), hypertrophy at 65-80% (6-12 reps), and endurance at 50-65% (12-20 reps). Recalculate your 1RM every 4 to 6 weeks as you progress.

Frequently Asked Questions

What is one rep max (1RM)?: One rep max is the maximum weight you can lift for a single repetition with proper form. It is the standard measure of maximal strength and is used to program training percentages.
How is 1RM calculated?: Our calculator uses the Epley formula: 1RM = weight × (1 + reps / 30). For example, if you bench press 80 kg for 8 reps, your estimated 1RM is 80 × (1 + 8/30) = 101.3 kg.