One-Repetition Maximum (1RM) Calculator

What is the one-repetition maximum (1RM) and why is it important

The one-repetition maximum (1RM) is the maximum weight you can lift once with proper technique in a given exercise. It is the most commonly used reference in strength training to programme loads, measure progress, and design personalised training plans.

Knowing your 1RM in key exercises such as the bench press, the squat and the deadlift allows you to work with precise percentages according to your goals:

• Maximum strength: work at 85-95% of your 1RM for 1-5 repetitions.
• Hypertrophy: work at 67-85% of your 1RM for 6-12 repetitions.
• Muscular endurance: work at 50-67% of your 1RM for 12-20 repetitions.

Epley's formula to calculate 1RM

Epley's formula is one of the most widely used and reliable methods to estimate your one-rep max without needing to perform an actual max attempt, which reduces the risk of injury:

1RM = Weight × (1 + Repetitions / 30)

For example, if you lift 80 kg for 8 repetitions: 1RM = 80 × (1 + 8/30) = 80 × 1.267 = approximately 101 kg.

Tips to safely estimate your 1RM

• Use a weight with which you can complete between 3 and 10 repetitions for a more accurate estimate.
• Make sure to perform each repetition with correct technique and a full range of motion.
• Warm up properly before performing test sets.
• Remember that the estimate is more accurate with fewer repetitions (3-6 reps) than with many (10+).

To plan your rest periods between sets, use our recovery time calculator. And if you need professional advice, consult our personal trainers.