What is a 3-Rep Max (3RM)?
A 3-rep max (3RM) represents the maximum weight you can lift for exactly three repetitions while maintaining proper form. This metric is fundamental in strength training for designing effective workout programs. Understanding your 3RM helps you train at the right intensity for building strength without the higher risk associated with maximal single-rep attempts.
The 3RM sits at approximately 93% of your one-rep maximum (1RM), making it a practical measure for both experienced lifters and those who prefer not to test their absolute max. Many training programs use 3RM-based loads because they provide sufficient stimulus for strength gains while allowing better technique maintenance.
The Formula Behind the Calculator
This calculator uses a two-step approach to determine your 3RM:
Step 1: Estimate Your 1RM (Epley Formula)
[\text{1RM} = \frac{\text{Weight Lifted}}{1.0278 - (0.0278 \times \text{Reps})}]
Step 2: Calculate Your 3RM
[\text{3RM} = \text{1RM} \times 0.93]
The Epley formula is widely used in strength training because of its accuracy across various rep ranges, particularly between 1-10 repetitions.
Calculation Example
Let's say you lifted 225 lbs for 5 reps and want to know your estimated 3RM:
Step 1: Calculate estimated 1RM
[\text{1RM} = \frac{225}{1.0278 - (0.0278 \times 5)} = \frac{225}{1.0278 - 0.139} = \frac{225}{0.8888} = 253.2 \text{ lbs}]
Step 2: Calculate 3RM
[\text{3RM} = 253.2 \times 0.93 = 235.5 \text{ lbs}]
Your estimated 3RM would be approximately 236 lbs.
Percentage-Based Rep Max Reference
Here is a general guide showing the relationship between rep maxes and percentages of 1RM:
- 1RM: 100%
- 2RM: 95%
- 3RM: 93%
- 4RM: 90%
- 5RM: 87%
- 6RM: 85%
- 8RM: 80%
- 10RM: 75%
When to Use Your 3RM
Knowing your 3RM is particularly useful for:
- Strength-focused training: Programs designed to build maximum strength often use 3RM loads
- Progressive overload: Tracking your 3RM over time shows strength progress
- Deload calculations: Using a percentage of your 3RM for lighter training weeks
- Competition preparation: Powerlifters and weightlifters use this for planning attempts
Tips for Accurate Estimation
- Use recent performance data: The weight and reps should be from a recent workout
- Maintain good form: Only count reps performed with proper technique
- Account for fatigue: Fresh sets provide more accurate estimates than sets performed when fatigued
- Test periodically: Re-test your actual 3RM occasionally to verify calculator accuracy