The Epley Formula Calculator estimates your One-Repetition Maximum (1RM)—the maximum amount of weight you can lift for a single repetition of an exercise. This tool is commonly used by strength athletes, trainers, and fitness professionals to plan workouts, track progress, and prevent overtraining.
Rather than testing your actual 1RM, which can be risky and physically demanding, this calculator lets you estimate it based on the weight you lift for multiple repetitions. It’s especially useful when designing progressive overload programs, adjusting training intensity, or choosing weights for hypertrophy or endurance phases.
Formula of Epley Formula Calculator
Detailed Breakdown:
- 1RM = Estimated one-rep max (in the same unit as input—pounds or kilograms)
- w = Weight lifted (for multiple reps)
- r = Number of repetitions (ideally ≤10 for accuracy)
The formula assumes that the relationship between reps and strength follows a linear pattern, which holds up well for moderate rep ranges.
Important Note: The Epley Formula works best for rep counts between 1 and 10. For higher reps, other formulas like the Brzycki or O’Conner may provide more accurate estimates.
Reference Table – Quick Estimates
| Reps | Weight (kg) | Estimated 1RM (kg) |
|---|---|---|
| 1 | 100 | 100 |
| 3 | 90 | 99 |
| 5 | 80 | 93 |
| 8 | 70 | 88.3 |
| 10 | 65 | 86.7 |
Example of Epley Formula Calculator
Suppose you bench press 85 kg for 5 reps. To estimate your 1RM:
1RM = 85 × (1 + 5 / 30)
1RM = 85 × (1 + 0.1667) ≈ 85 × 1.1667 ≈ 99.17 kg
Your estimated one-repetition maximum is approximately 99.2 kg.
This means your training loads can be programmed as a percentage of 99.2 kg—for example:
- 70% 1RM = 69.4 kg for hypertrophy
- 85% 1RM = 84.3 kg for strength
Most Common FAQs
Yes, for rep ranges up to 10, it provides a fairly accurate estimate. It’s widely used in strength and conditioning.
Yes, you can apply it to squats, deadlifts, bench presses, and even isolation movements like bicep curls—just keep form and rep quality consistent.
Testing your actual 1RM can increase injury risk. Using a calculated estimate is safer, faster, and still useful for programming effective workouts.