426 lb works out to 4x45 + 1x10 per side plus the bar — call it 425 lb in practice, since gyms rarely stock the odd change. 5 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 365 lb set represents about 86% of the estimated max.
How far 426 lb can be trusted
Five reps is the most common way people estimate a max and the rep count these equations were checked against most often. The seven put your max between 411 and 434 lb. A set of five is short enough that breathing and pacing do not dominate it, so what the bar does on the fifth rep is a fair proxy for what it would do on a single — which is the assumption the whole method rests on.
Training loads from a 426 lb max
Programmes are written as percentages of the max, not as absolute weights. From 426 lb, rounded to the nearest 5 lb:
| Percentage | Load | Typical set |
|---|---|---|
| 95% | 405 lb | Heavy single |
| 90% | 385 lb | Doubles and triples |
| 85% | 360 lb | Sets of four to five |
| 80% | 340 lb | Sets of six |
| 75% | 320 lb | Sets of eight |
| 70% | 300 lb | Volume work, ten or more |
426 lb is 4x45 + 1x10 per side plus the bar, 425 lb loaded. At this load the 23 lb the formulas disagree by is bigger than a pair of 10s, which is a good argument for programming off the lower estimate — 411 lb — and letting the bar prove you wrong rather than the other way round. Warm-up jumps also get long here; work up in percentages rather than in fixed plate increments.
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 365 lb for 5 reps; the headline figure is their median. All seven assume a set taken close to failure with clean technique. At 5 reps you are still inside the fitted band, but conditioning is now affecting the result alongside strength, and the seven have begun to curve away from each other. 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 426 lb. This is a training estimate, not medical advice.