186 lb works out to 1x45 + 1x25 per side plus the bar — call it 185 lb in practice, since gyms rarely stock the odd change. 4 reps sits comfortably inside the 2-to-10 range these formulas were fitted on, so this estimate is about as reliable as the method gets. Your 165 lb set represents about 89% of the estimated max.
How far 186 lb can be trusted
Four reps still sits in the well-behaved part of the range. The seven equations return 180 to 192 lb, and most of that 6.5% gap is them disagreeing about how fast strength falls off with reps rather than any of them being wrong. A set of four is also long enough that fatigue in the last rep is visible: if rep four was a grind, this estimate is honest; if it moved easily, 186 lb is on the low side.
Training loads from a 186 lb max
Programmes are written as percentages of the max, not as absolute weights. From 186 lb, rounded to the nearest 5 lb:
| Percentage | Load | Typical set |
|---|---|---|
| 95% | 175 lb | Heavy single |
| 90% | 165 lb | Doubles and triples |
| 85% | 160 lb | Sets of four to five |
| 80% | 150 lb | Sets of six |
| 75% | 140 lb | Sets of eight |
| 70% | 130 lb | Volume work, ten or more |
186 lb loads as 1x45 + 1x25 per side plus the bar, or 185 lb on the bar. Round every figure in that table to the nearest 5 lb and stop there — the seven formulas disagree by 12 lb on this set, so chasing a two-pound difference is chasing noise. If your gym stocks 2.5 lb pairs, save them for the top two rows, where a small miss costs the most reps.
The formulas behind this answer, and their limitations
The table above the fold is Epley (1985), Brzycki (1993), Lombardi (1989), O'Conner (1989), Wathan (1994), Lander (1985) and Mayhew (1992), each applied to 165 lb for 4 reps; the headline figure is their median. All seven assume a set taken close to failure with clean technique. At 4 reps you are inside the band they were fitted on, so the largest error here is not the equation but judging how close your set really was to failure — three reps left in the tank reads exactly the same to them. They also under-rate strong, experienced lifters, who hold a higher percentage of max at any rep count than the regression average. The full account — the populations behind each equation, what a bounced rep does to it, and why we stop at ten reps — is set out on the methodology page. Warm up thoroughly and use safety bars or a spotter before going anywhere near 186 lb. This is a training estimate, not medical advice.