One Rep Max Calculator

What is a One Rep Max (1RM)?

Your one-rep max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise through a full range of motion. It is the gold standard for measuring pure strength.

However, testing your true 1RM frequently can be dangerous and highly taxing on your central nervous system. That's why strength athletes and coaches use 1RM calculators to estimate max strength based on submaximal sets (like a heavy set of 3, 5, or 8 reps).

How Do These Formulas Work?

There is no single "perfect" formula for everyone, as muscle fiber composition and lifting experience vary. We provide the three most proven formulas so you can find the average:

• Epley Formula: Invented by Boyd Epley in 1985. It tends to be highly accurate for lower body lifts like the squat and deadlift. Weight × (1 + 0.0333 × Reps)
• Brzycki Formula: Created by Matt Brzycki in 1993. It's often considered the most accurate formula for fewer than 10 repetitions and is widely used for upper body lifts like the bench press. Weight × (36 / (37 - Reps))
• Lombardi Formula: Proposed by Maurice Lombardi in 1989. It is slightly more forgiving for higher rep ranges. Weight × Reps^0.10

Training with Percentages

Once you know your estimated 1RM, you can program your training loads effectively. Different percentages target different physical adaptations:

• 85% - 100%: Maximum Strength (1-5 reps)
• 70% - 85%: Hypertrophy / Muscle Growth (6-12 reps)
• 50% - 70%: Muscular Endurance (15+ reps)

Use the training load chart generated above to instantly find the weight you should be putting on the bar for your specific goals.