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One Rep Max Calculator

Calculate your theoretical one-rep maximum (1RM) for major compound movements and get training percentages for different rep ranges.

Enter Your Lift Data

Instructions

  • • Enter a weight you can lift for 1-15 reps
  • • Use your most recent maximum effort
  • • Ensure proper form was maintained
  • • Results are estimates for training purposes

How to Use This Tool

Step-by-Step Instructions

  1. Choose your unit system: Select between Metric (kg) or Imperial (lbs) for weight measurements
  2. Enter the weight lifted: Input the maximum weight you can lift for the specified number of reps
  3. Enter number of reps: Input how many repetitions you completed with that weight (1-15 reps)
  4. Ensure proper form: Only use lifts where you maintained proper form throughout all repetitions
  5. Calculate: Click "Calculate 1RM" to get your estimated one-rep maximum and training percentages
  6. Review results: Use the training percentages to plan your workout intensities

Best Practices

  • • Use recent maximum effort lifts (within 1-2 weeks)
  • • Ensure you were well-rested when performing the lift
  • • Only count reps with full range of motion
  • • Use compound movements (squat, bench, deadlift)
  • • Update calculations regularly as you get stronger

Safety Tips

  • • Always warm up properly before heavy lifts
  • • Use a spotter when available
  • • Progress gradually - don't jump to max immediately
  • • Listen to your body and avoid lifting when fatigued
  • • These are estimates - actual performance may vary

Understanding One Rep Max

Your one-rep maximum (1RM) is the maximum weight you can lift for one complete repetition with proper form. This calculator uses the Epley formula to estimate your 1RM based on submaximal lifts, which is safer than attempting true maximum lifts.

Training Applications

  • 90-95%: Strength and power development (1-3 reps)
  • 80-90%: Maximum strength building (3-6 reps)
  • 70-80%: Strength and muscle building (6-10 reps)
  • 60-70%: Muscle endurance and hypertrophy (10+ reps)

Safety Considerations

Always warm up properly before attempting heavy lifts. Use spotters when available, maintain proper form, and progress gradually. These calculations are estimates - actual performance may vary based on factors like fatigue, technique, and training experience.

Frequently Asked Questions

How accurate is the one rep max calculation?

The Epley formula is widely used and generally accurate for most people, especially for reps in the 2-10 range. Accuracy may decrease for very high reps (15+) or if you're a beginner or advanced powerlifter.

Should I test my actual 1RM based on this calculation?

Use this as a guide, but approach actual 1RM testing cautiously. Always warm up properly, use spotters, and consider testing with an experienced coach, especially for compound movements.

Which exercises work best with this calculator?

This calculator works best with compound movements like bench press, squat, deadlift, and overhead press. It's less accurate for isolation exercises or movements with different strength curves.

How often should I recalculate my 1RM?

Recalculate every 4-8 weeks as you get stronger, or whenever you achieve a new rep max in your training. This ensures your training percentages stay accurate and progressive.

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