300 lb works out to 2x45 + 1x35 + 1x5 per side plus the bar — call it 305 lb in practice, since gyms rarely stock the odd change. 3 reps sits at the reliable end of the range these formulas were fitted on, so the 22 lb spread here is about as tight as the method gets. Your 275 lb set represents about 92% of the estimated max.
Why 3 reps gives a tight estimate
A triple is close to the best case for this method. The low end of the two-to-ten band is where these regressions were sampled most heavily, and it shows here — the seven land within 22 lb of each other, 7.3% of the estimate, which is small enough that choosing a different formula would not change how you train. If the third rep slowed down but the bar never stalled, 300 lb is a defensible working number.
Training loads from a 300 lb max
Programmes are written as percentages of the max, not as absolute weights. From 300 lb, rounded to the nearest 5 lb:
| Percentage | Load | Typical set |
|---|---|---|
| 95% | 285 lb | Heavy single |
| 90% | 270 lb | Doubles and triples |
| 85% | 255 lb | Sets of four to five |
| 80% | 240 lb | Sets of six |
| 75% | 225 lb | Sets of eight |
| 70% | 210 lb | Volume work, ten or more |
300 lb is 2x45 + 1x35 + 1x5 per side plus the bar — 305 lb loaded. Plate maths gets easier at this weight, because most of the jumps land on whole 10s and 25s. The bottom three rows of that table are worth rounding generously; the top two are where you want to be precise, since 5 lb at 95% of 300 lb is the difference between a single and a missed single.
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 275 lb for 3 reps; the headline figure is their median. All seven assume a set taken close to failure with clean technique. At 3 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 300 lb. This is a training estimate, not medical advice.