w × (1 + r/40) — A calmer, more conservative estimate for lifters who want a quick reality check before loading the bar.
Strength levels for a 200lb male, age 30 lifting 253lb in each lift type · enter your details.
OConner algorithm
| Reps | Weight (lb) |
|---|---|
| 1RM | 253lb |
| 2RM | 241lb |
| 3RM | 235lb |
| 4RM | 230lb |
| 5RM(current) | 225lb |
| 6RM | 220lb |
| 7RM | 215lb |
| 8RM | 211lb |
| 9RM | 207lb |
| 10RM | 202lb |
| 20RM | 169lb |
Based on 253lb estimated max
| Intensity | Weight (lb) |
|---|---|
| 100% | 253lb |
| 95% | 240lb |
| 90% | 228lb |
| 85% | 215lb |
| 80% | 202lb |
| 75% | 190lb |
| 70% | 177lb |
| 65% | 164lb |
| 60% | 152lb |
| 55% | 139lb |
| 50% | 127lb |
Input: Input set: 225 lb x 5 reps
Calculation: Formula: 225 x (1 + 5/40) = 253.1
Result: Estimated 1RM: 253 lb
O'Conner tends to estimate slightly lower than Epley, so it is a useful conservative check when you want to avoid inflated higher-rep projections.
O'Conner is a good formula to check when you want a projected max that does not get carried away. It gives you a quick conservative read, then lets you compare that answer against the more aggressive formulas before planning attempts or warm-ups.
In practice, that is how many lifters use it. O'Conner usually comes out lower on the same set, so it works as a quick check when you want to avoid letting a generous estimate drive your training max too high.
O'Conner is handy when you want a cautious projected max to base your percentages on. If you would rather start a little lighter and adjust up than overshoot from the first warm-up jump, the conservative estimate can be helpful.
