One Rep Max Calculator

Calculate your one-repetition maximum (1RM) - the maximum weight you can lift for a single repetition of an exercise. This calculator uses three widely-accepted formulas to provide accurate estimates of your maximum strength.

How to Use This Calculator

1. Enter the weight you lifted (in pounds or kilograms)
2. Input the number of repetitions you performed
3. Click “Calculate” to see your estimated 1RM
4. View results from three different formulas for better accuracy

Understanding Your Results

The calculator provides three different estimates using well-established formulas:

Epley Formula

• Most widely used formula
• Generally accurate across different exercises
• Formula: 1RM = weight × (1 + 0.0333 × reps)

Brzycki Formula

• Tends to be more accurate for lower rep ranges
• Often used in powerlifting
• Formula: 1RM = weight × (36 / (37 - reps))

Lombardi Formula

• Known for accuracy across varied rep ranges
• Formula: 1RM = weight × (reps)^0.10

Important Notes

• Best results when using reps between 1-10
• Accuracy decreases with higher rep ranges
• Results are estimates; actual 1RM may vary
• Not recommended for beginners
• Always warm up properly before testing maximal weights

Training Applications

1. Program Design

   • Use percentages of 1RM for training programs
   • Plan progressive overload
   • Set realistic training goals

2. Strength Assessment

   • Track progress over time
   • Compare strength across different exercises
   • Evaluate training program effectiveness

3. Competition Preparation

   • Estimate competition attempts
   • Plan warm-up sets
   • Set realistic competition goals

Safety Guidelines

1. Proper Form

   • Maintain correct technique
   • Don’t sacrifice form for weight
   • Use appropriate equipment

2. Progression

   • Increase weight gradually
   • Allow adequate recovery
   • Listen to your body

3. Testing Frequency

   • Don’t test 1RM too frequently
   • Ensure proper recovery between tests
   • Consider using submaximal testing

Frequently Asked Questions

How accurate are these calculations?

The formulas provide estimates based on scientific research and practical application. Accuracy tends to be higher when using weights you can lift for 1-10 repetitions with good form.

Which formula should I trust most?

Each formula has its strengths. The Epley formula is most widely used, but comparing all three can give you a good range to work with. Your actual 1RM may fall somewhere within this range.

Can I use this for any exercise?

While these formulas work for most resistance exercises, they’re most accurate for compound movements like squats, deadlifts, bench press, and overhead press.

How often should I test my 1RM?

Direct 1RM testing should be done sparingly, typically every 8-12 weeks or at the end of a training cycle. Use this calculator for more frequent estimates without maximal loading.