About One Rep Max Calculator

Your comprehensive tool for calculating one-repetition maximum and planning effective strength training programs.

What is One Rep Max (1RM)?

Your one-repetition maximum (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise with proper form. It's a fundamental metric in strength training used to:

  • Measure your current strength levels
  • Track progress over time
  • Design effective training programs
  • Calculate appropriate training weights for different rep ranges
  • Set realistic strength goals

How It Works

Our calculator uses three scientifically validated formulas to estimate your 1RM based on the weight you lifted and the number of repetitions performed:

Epley Formula

1RM = Weight × (1 + Reps / 30)

Most accurate for 4-6 rep ranges. Widely used in strength training programs.

Brzycki Formula

1RM = Weight × (36 / (37 - Reps))

Best for lower rep ranges (1-10 reps). Conservative estimates.

Lander Formula

1RM = (100 × Weight) / (101.3 - 2.67123 × Reps)

Effective for moderate rep ranges. Balanced approach.

Key Features

Multi-Formula Calculation

Compare results from three validated formulas to get the most accurate estimate of your 1RM.

Unit Conversion

Seamlessly switch between kilograms and pounds with automatic conversion.

Training Weight Calculator

Generate percentage-based training weights for different intensity levels.

Exercise History

Track your progress over time with saved exercise history and progress indicators.

Preset Exercises

Quick access to common exercises organized by movement patterns.

Export & Print

Save or print your training weights for easy reference at the gym.

Best Practices

  • •Use proper form: Only count reps performed with correct technique.
  • •Test in lower rep ranges: 1RM estimates are most accurate when using 1-10 reps.
  • •Warm up properly: Always perform adequate warm-up sets before testing.
  • •Be conservative: When in doubt, start with lighter training weights and progress gradually.
  • •Retest regularly: Update your 1RM estimates every 4-6 weeks to track progress.

Important Safety Notice

This calculator provides estimates based on mathematical formulas. Always prioritize safety when lifting heavy weights. Consider working with a qualified coach or spotter, especially when attempting near-maximal loads. Consult with a healthcare professional before beginning any new exercise program.

Start Calculating Your 1RM