Estimate your one-rep max from any set with the Epley and Brzycki formulas, then read training weights from 100% down to 50% of that max. Runs entirely in your browser — your numbers never leave this device.
| % of 1RM | Weight (kg) | Typical reps |
|---|---|---|
| 100% | 114.58 | 1 |
| 95% | 108.85 | 2 |
| 90% | 103.13 | 3–4 |
| 85% | 97.4 | 5–6 |
| 80% | 91.67 | 7–8 |
| 75% | 85.94 | 9–10 |
| 70% | 80.21 | 11–12 |
| 65% | 74.48 | 13–15 |
| 60% | 68.75 | 16–20 |
| 55% | 63.02 | 21–24 |
| 50% | 57.29 | 25–30 |
Both formulas estimate a max you have not attempted. Never load a bar to a predicted 1RM without a warm-up progression and, for free-weight lifts, a spotter.
A one-rep max (1RM) is the heaviest load you can lift once with good form, and most training programmes are written as percentages of it — but testing a true max is tiring and, for beginners, risky. The two classic estimators infer it from a submaximal set instead. Epley's formula, 1RM = w × (1 + reps/30), grows linearly: every extra rep adds a thirtieth of the weight lifted. Brzycki's formula, 1RM = w × 36/(37 − reps), curves upward instead, which is why the two agree closely on moderate sets — both give 106.67 from an 80 kg set of 10 — and drift apart at the extremes. This page shows both plus their average, so the spread between them is visible rather than hidden.
Accuracy is a property of the set you feed in. Both formulas were fitted on sets in roughly the 2–10 rep range; below that they are nearly exact, and above 10 reps muscular endurance starts to dominate and both estimates inflate — Brzycki faster than Epley, as the 100 kg × 12 comparison (Epley 140.0, Brzycki 144.0) shows. Brzycki is undefined at 37 reps, where its denominator reaches zero, and this calculator says so rather than printing a nonsense number.
The percentage table turns the estimate into working weights: 100% down to 50% of the chosen 1RM in 5% steps, each row paired with the reps that load typically allows — 1 at 100%, around 5–6 at 85%, around 25–30 at 50%. Those rep guidelines are the standard published pairing, a planning aid rather than a guarantee, since they vary by lift and lifter. An estimate is not an attempt: never load a bar to a predicted max without a warm-up progression and a spotter for free-weight lifts.
Neither wins everywhere, which is why this page shows both and their average. They agree almost exactly in the 5–10 rep range (both give 106.67 kg for 80 kg × 10). At low reps both are close to a tested max; at high reps Brzycki climbs faster and overestimates sooner. If the two disagree by more than about 5%, retest with a heavier, lower-rep set rather than picking the answer you prefer.
Because the relationship between reps and load stops being mostly about strength. A set of 15–20 is limited partly by muscular endurance and tolerance for discomfort, which vary far more between lifters than strength does, so any formula fitted on strength sets inflates the estimate. A heavy set of 3–5 reps is the most reliable input you can give either formula.
The formulas were developed on big barbell lifts — squat, bench press, deadlift — and work best there. They are rough on single-joint isolation exercises, where technique and endurance dominate, and meaningless for bodyweight movements. Use the estimate for the lift you actually tested, not transferred to a different movement.
As the menu your programme is written in. Heavy strength work lives at 85–95% for low reps, general training at 70–80%, and light or speed work at 50–65%. Pick the row matching your programme's prescription, load that weight (rounded to the plates you actually own), and expect the reps guideline to be approximate — leave a rep or two in reserve rather than grinding to failure on estimated loads.
Only if you are an experienced lifter, the lift is one you can fail safely (spotter, rack safeties), and a tested number genuinely matters — for a competition or a programme milestone. For everyday training the estimate from a hard set of 3–5 reps carries the same programming value at a fraction of the injury risk and fatigue cost.
More in Sports & Fitness Calculators · Browse all tools