79 lb works out to 1x10 + 1x5 per side plus the bar — call it 75 lb in practice, since gyms rarely stock the odd change. 2 reps sits at the reliable end of the range these formulas were fitted on, so the 7 lb spread here is about as tight as the method gets. Your 75 lb set represents about 95% of the estimated max.
Why 2 reps gives a tight estimate
A double is the shortest set these seven equations accept, and it is where they agree most closely. Every one of them was regressed on sets of two to ten reps, so two sits at the near edge of the fitted band rather than outside it, and the 7 lb between 77 and 84 lb is about as narrow as this method ever gets. The uncertainty at two reps is not in the arithmetic, it is in the set: a double you could have taken one rep further looks identical on paper to one that genuinely stopped you.
Training loads from a 79 lb max
Programmes are written as percentages of the max, not as absolute weights. From 79 lb, to the nearest pound, because 5 lb steps collapse into each other at this load:
| Percentage | Load | Typical set |
|---|---|---|
| 95% | 75 lb | Heavy single |
| 90% | 71 lb | Doubles and triples |
| 85% | 67 lb | Sets of four to five |
| 80% | 63 lb | Sets of six |
| 75% | 59 lb | Sets of eight |
| 70% | 55 lb | Volume work, ten or more |
At this end of the rack almost none of those percentages lands on a plate you own. 79 lb itself builds as 1x10 + 1x5 per side plus the bar, which is 75 lb — near enough, and the miss is smaller than the 7 lb the seven formulas disagree by. This is the weight range where a pair of 2.5 lb or 1.25 lb plates genuinely earns its place, because a 10 lb jump here is a much larger proportional step than it is at 300.
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 75 lb for 2 reps; the headline figure is their median. All seven assume a set taken close to failure with clean technique. At 2 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 79 lb. This is a training estimate, not medical advice.