What is one rep max and why does it matter?

One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition of an exercise with proper form. It matters because it's the foundation for programming strength training. Most workout programmes prescribe weights as percentages of your 1RM (e.g., '5 sets of 5 at 75% 1RM').

Which 1RM formula is most accurate?

Research suggests the Epley and Brzycki formulas are most accurate for reps between 1-10. The Brzycki formula tends to be slightly better for lower rep ranges (1-6), while Epley may be more accurate for higher reps (7-10). All formulas become less accurate above 10 reps.

How do I safely test my one rep max?

To safely test your 1RM: warm up thoroughly, use a spotter for compound lifts, start at about 80% of your estimated max, increase weight in small increments (2-5%), rest 3-5 minutes between attempts, and stop when form breaks down. Never attempt a true 1RM without proper experience.

How can I improve my one rep max?

To improve your 1RM: train with progressive overload, include both heavy (85-95% 1RM) and moderate (70-80% 1RM) weights, focus on compound movements, ensure adequate rest between sessions, eat sufficient protein, and consider periodization in your training programme.

One Rep Max Calculator

Estimate your one rep max (1RM) using 7 scientific formulas. Get training zone recommendations for strength, hypertrophy, power, and endurance.

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Your One Rep Max is the maximum weight you can lift for a single repetition. Most adults can lift 1.5x their bodyweight on deadlift as a beginner.

Calculate your exact 1RM from any rep range below.

Enter Your Lift

Weight Lifted (lbs)

Repetitions: 5

Most accurate for 1-10 reps

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Last updated: January 2026 • Built with care by iForge Apps

How to use this tool

1

Select your preferred unit system (Imperial or Metric)

2

Enter the weight you lifted

3

Select the number of reps you completed (1-15)

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