If you want to find out how strong you really are without lifting your maximum weight, the Epley Formula is one of the most trusted and accurate ways to calculate your 1 Rep Max (1RM).
This method helps you estimate the heaviest weight you can lift for one complete repetition in any exercise—whether it’s the bench press, squat, or deadlift—without the risk of injury or overtraining.
What Is the Epley Formula?
The Epley Formula was developed by Dr. Boyd Epley, one of the pioneers of strength and conditioning.
It provides a simple and reliable way to estimate your one repetition maximum (1RM) using the weight you lift and the number of repetitions you perform.
Instead of testing your maximum lift directly, which can be dangerous, the Epley formula lets you predict your 1RM safely and accurately.
Epley Formula for 1 Rep Max
The formula is as follows:
1RM = Weight × (1 + (Reps ÷ 30))
Where:
- Weight = the amount of weight you lifted (in kg or lbs)
- Reps = the number of repetitions completed
This gives you an estimated one rep max (1RM) — the maximum weight you could lift for one repetition.
Example of Epley Formula Calculation
Let’s say you lifted 100 kg for 5 reps on the bench press.
1RM = 100 × (1 + (5 ÷ 30))
1RM = 100 × (1 + 0.1667)
1RM = 100 × 1.1667
1RM = 116.7 kg
Your estimated 1 Rep Max is 116.7 kg.
This means if you were to lift only one rep with full strength, you could lift around 116–117 kg.
Why Use the Epley Formula Instead of Testing Your 1RM Directly?
Testing your one rep max directly can be risky, especially for beginners or when training alone. The Epley formula removes that risk by letting you estimate your max strength safely.
Benefits of Using the Epley Formula
- Safer than performing a true 1RM test
- Simple and accurate for most lifters
- Helps design effective training programs
- Saves time during workouts
- Useful for all major compound lifts
How Accurate Is the Epley Formula?
The Epley formula is most accurate when used with 6 or fewer reps.
As the number of reps increases, accuracy decreases slightly due to fatigue and form breakdown.
For the best results:
- Keep your rep range between 1–6 reps
- Maintain proper form during every rep
- Record your results consistently
Training Percentages Based on Epley 1RM Calculation
Once you know your Epley 1RM, you can use it to plan your workouts more effectively.
Here’s a general guide for training percentages:
| Training Goal | % of 1RM | Reps per Set |
|---|---|---|
| Strength | 85–100% | 1–5 reps |
| Muscle Growth (Hypertrophy) | 65–85% | 6–12 reps |
| Endurance | 50–65% | 12+ reps |
This allows you to adjust your training intensity depending on whether your goal is strength, size, or endurance.
Epley Formula vs. Other 1RM Formulas
While there are several formulas to calculate 1RM (like Brzycki or Lombardi), the Epley Formula remains one of the most widely used due to its simplicity and consistency.
| Formula | Equation | Best Used For |
|---|---|---|
| Epley | 1RM = Weight × (1 + (Reps ÷ 30)) | General strength training |
| Brzycki | 1RM = Weight × (36 ÷ (37 − Reps)) | Moderate rep ranges |
| Lombardi | 1RM = Weight × (Reps ^ 0.10) | Higher rep sets |
Most athletes and coaches prefer Epley’s formula because it works well for most exercises and fitness levels.
Exercises You Can Use the Epley Formula For
You can calculate your estimated 1RM using the Epley formula for almost any compound lift, including:
- Bench Press
- Squat
- Deadlift
- Overhead Press
- Barbell Row
These are the most effective exercises for measuring and improving total body strength.
Tips for Accurate 1RM Estimation
- Always warm up before heavy sets
- Use consistent form on every rep
- Avoid testing when tired or sore
- Write down your weights and reps
- Test periodically (every 8–12 weeks)
Conclusion
The Epley Formula is one of the most effective and widely used methods for estimating your 1 Rep Max (1RM) safely.
It gives you a clear understanding of your strength levels, helps track progress, and allows you to structure training based on precise percentages.
Whether your goal is strength, muscle gain, or endurance, knowing your Epley 1RM is the key to training smarter and achieving better results in less time.