One Rep Max Calculator
Calculate your one-rep max (1RM) using multiple proven formulas. Plan your training percentages and rep ranges effectively.
Lift Details
Enter the number of reps completed with good form (1-30)
Formula Comparison
Most commonly used, accurate for 1-10 reps
Very accurate for lower rep ranges (1-10)
Good for moderate rep ranges
Tends to underestimate for higher reps
Simple formula, slightly lower estimates
Good across all rep ranges
Estimated One Rep Max
115 kg
Based on 100 kg for 5 reps
Training Percentages
| % | Weight | Reps |
|---|---|---|
| 100% | 115 kg | 1 |
| 95% | 109 kg | 2 |
| 90% | 103 kg | 3-4 |
| 85% | 98 kg | 5-6 |
| 80% | 92 kg | 7-8 |
| 75% | 86 kg | 9-10 |
| 70% | 80 kg | 11-12 |
| 65% | 75 kg | 13-15 |
| 60% | 69 kg | 16-20 |
| 55% | 63 kg | 20+ |
Safety Tips for Max Attempts
- •Always warm up thoroughly before attempting heavy lifts
- •Use a spotter when testing your true 1RM
- •Don't test 1RM when fatigued or recovering from injury
- •Estimated 1RM from 3-5 rep sets is often safer than true max attempts
How is 1RM Calculated?
There are several formulas to estimate your one-rep max. Each has different accuracy depending on your rep range and training experience.
Why Use 1RM?
Knowing your 1RM helps you plan training at the right intensity. Most strength programs are based on percentages of your max lift.
Training Rep Ranges
Different percentages of your 1RM target different training goals:
- 💪1-5 reps (85-100%): Maximum strength development
- 🏋️6-12 reps (65-85%): Muscle size and moderate strength
- 🔄12-20 reps (50-65%): Muscular endurance and conditioning
Tips for Accurate Estimation
- 1Use a weight you can lift with good form for 3-10 reps for best accuracy
- 2Higher rep sets (10+) become less accurate as form often degrades
- 3Test periodically to track strength progress
- 4Different formulas work better for different people - find your best match
- 5Your true 1RM may be 5-10% different from calculated estimates