w × (1 + r/30) — The formula most lifters know first - and the one many start doubting once reps climb into optimistic territory.
Strength levels for a 200lb male, age 30 lifting 263lb in each lift type · enter your details.
Epley algorithm
| Reps | Weight (lb) |
|---|---|
| 1RM | 263lb |
| 2RM | 247lb |
| 3RM | 239lb |
| 4RM | 232lb |
| 5RM(current) | 225lb |
| 6RM | 219lb |
| 7RM | 213lb |
| 8RM | 208lb |
| 9RM | 202lb |
| 10RM | 197lb |
| 20RM | 158lb |
Based on 263lb estimated max
| Intensity | Weight (lb) |
|---|---|
| 100% | 263lb |
| 95% | 250lb |
| 90% | 237lb |
| 85% | 224lb |
| 80% | 210lb |
| 75% | 197lb |
| 70% | 184lb |
| 65% | 171lb |
| 60% | 158lb |
| 55% | 145lb |
| 50% | 132lb |
Input: Input set: 225 lb x 5 reps
Calculation: Formula: 225 x (1 + 5/30) = 262.5
Result: Estimated 1RM: 263 lb
This is why Epley is a common default for moderate-rep working sets: the math is simple and the estimate lands close to what most lifters expect.
This page is tuned for lifters who want a fast Epley formula 1RM calculation from a normal working set, then compare that result against the other major equations. Reynolds, Gordon, and Robergs found that "5RM data produced the greatest prediction accuracy", which lines up with how most lifters use Epley in practice.
The Epley formula is 1RM = weight × (1 + reps/30). For example, if you lift 225 lb for 5 reps: 225 × (1 + 5/30) = 262.5, giving an estimated 1RM of about 263 lb. Developed by Boyd Epley in 1985, it's one of the most widely cited 1RM equations. A 2006 Journal of Strength and Conditioning Research study found that 5RM data produced the greatest prediction accuracy, which aligns with how most lifters use the Epley formula in practice.
Epley is most reliable in the 3–10 rep range. Above 10 reps, fatigue and technique breakdown introduce more noise into the estimate. That same 2006 prediction accuracy study recommended using no more than 10 repetitions for linear 1RM predictions. For higher-rep sets, consider comparing Epley against the Mayhew formula, which uses an exponential curve designed for those ranges.
Epley usually gives the higher estimate, especially as reps climb. Brzycki tends to stay stricter, which is why many lifters compare both before deciding whether their projected max looks realistic or inflated.
