100w ÷ (101.3 − 2.671r) — The overlooked middle-ground formula - useful when Epley feels bold, Brzycki feels strict, and you want a tie-breaker.
Strength levels for a 200lb male, age 30 lifting 256lb in each lift type · enter your details.
McGlothin algorithm
| Reps | Weight (lb) |
|---|---|
| 1RM | 256lb |
| 2RM | 246lb |
| 3RM | 239lb |
| 4RM | 232lb |
| 5RM(current) | 225lb |
| 6RM | 218lb |
| 7RM | 211lb |
| 8RM | 205lb |
| 9RM | 198lb |
| 10RM | 191lb |
| 20RM | 123lb |
Based on 256lb estimated max
| Intensity | Weight (lb) |
|---|---|
| 100% | 256lb |
| 95% | 243lb |
| 90% | 230lb |
| 85% | 218lb |
| 80% | 205lb |
| 75% | 192lb |
| 70% | 179lb |
| 65% | 166lb |
| 60% | 154lb |
| 55% | 141lb |
| 50% | 128lb |
Input: Input set: 225 lb x 5 reps
Calculation: Formula: 100 x 225 / (101.3 - 2.671 x 5) = 255.9
Result: Estimated 1RM: 256 lb
McGlothin stays fairly steady across a broad middle rep range, which makes it useful when you want a calmer linear comparison.
McGlothin is easy to miss because it rarely wins the popularity contest, but that is exactly why it is useful. When Epley feels high and Brzycki feels low, McGlothin often becomes the tie-breaker worth checking.
Mostly because Epley and Brzycki dominate the conversation. McGlothin is less famous, not useless. In practice, it can be helpful precisely because it often lands between the aggressive and conservative estimates on the same set.
Check McGlothin when the usual formulas disagree enough to make your projected max feel uncertain. It is a good tie-breaker when you want a steady linear estimate before choosing training percentages or an attempt goal.
