Your one-rep max, read three ways from one heavy set
A one-rep max calculator built around the disagreement: switch equations on the same set, read the percentage table down to 50%, and see how much the rep count you used is worth trusting.
One-rep max reference: load charts, equations, and zones
Every percentage on a program sheet traces back to a single number, and coaches read most of that sheet off lookup charts rather than a calculator: reps-to-percentage for prescribing load, and the published equations for estimating the max in the first place. Collected here are the tables a lifter actually consults: the NSCA load chart, the seven documented 1RM equations, the intensity zones each percentage band belongs to, and the RPE and warm-up loads that sit around a working set.
Percentage of 1RM by reps
The standard load chart (Baechle and Earle, NSCA) maps a rep target to the percentage of a one-rep max that typically allows it. Read it forward to prescribe (what should a set of 5 weigh) or backward to estimate: press 185 lb for 5 clean reps, land near 87%, and a max around 213 lb follows. The chart is population-average, so a beginner and a veteran on the same lift can sit a few percent apart at the same rep count.
| Reps | %1RM | Reps | %1RM |
|---|---|---|---|
| 1 | 100% | 8 | 80% |
| 2 | 95% | 9 | 77% |
| 3 | 93% | 10 | 75% |
| 4 | 90% | 12 | ~70% |
| 5 | 87% | 15 | ~65% |
| 6 | 85% | 20 | ~60% |
| 7 | 83% |
Rows at 12 reps and beyond are extrapolations that drift by lifter and by lift; treat anything past a heavy set of 10 as a rough anchor, not a prescription.
Published 1RM equations
Seven equations recur across the strength literature and the reference sites. Onemax ships the first three on screen; the rest are here for cross-checking a number against a second source. In every row, w is the weight lifted and r is clean reps performed to near-failure.
| Equation | Source | Formula | Behaviour |
|---|---|---|---|
| Epley | Epley, 1985 | w · (1 + r/30) | Linear; reads above the bar weight from rep 1 |
| Brzycki | Brzycki, 1993 | w · 36 / (37 − r) | Undefined near r = 37; conservative at low reps |
| Lombardi | Lombardi, 1989 | w · r^0.10 | Power curve; flattens fastest past ~10 reps |
| Lander | Lander, 1985 | 100w / (101.3 − 2.67123r) | Tracks close to Brzycki |
| Mayhew | Mayhew et al., 1992 | 100w / (52.2 + 41.9 · e^(−0.055r)) | Exponential; fit to bench press data |
| O'Conner | O'Conner et al., 1989 | w · (1 + 0.025r) | Gentlest linear slope of the set |
| Wathan | Wathan, 1994 | 100w / (48.8 + 53.8 · e^(−0.075r)) | Exponential; holds across a wide rep range |
All seven were fit mostly to sets under six reps, which is why they converge near a heavy single and fan apart as the rep count climbs into double digits.
Training intensity zones
Each percentage band lines up with a training goal, a working rep range, and a rest interval, which is the bridge from an estimated max to a written session. Bands overlap on purpose: 80% can serve either a strength or a hypertrophy day depending on how many sets and reps sit around it.
| Goal | %1RM | Reps | Rest |
|---|---|---|---|
| Maximal strength | ≥ 85% | 1–5 | 3–5 min |
| Power (single-effort) | 80–90% | 1–2 | 2–5 min |
| Power (multi-effort) | 75–85% | 3–5 | 2–5 min |
| Hypertrophy | 67–85% | 6–12 | 30–90 s |
| Muscular endurance | ≤ 67% | 12+ | ≤ 30 s |
Loading by RPE and warm-up ramp
Autoregulation swaps a fixed percentage for a rating of perceived exertion, where RPE 10 means no reps left in the tank and each point below adds one rep in reserve. The chart maps an RPE and rep count to an approximate percentage of max, so a lifter can adjust load to the day instead of a spreadsheet.
| Reps | RPE 10 | RPE 9 | RPE 8 | RPE 7 |
|---|---|---|---|---|
| 1 | 100% | 96% | 92% | 89% |
| 3 | 92% | 89% | 86% | 84% |
| 5 | 86% | 84% | 81% | 79% |
A warm-up ramp climbs to that first working set as a share of its weight, adding load while shedding reps so the nervous system is primed but not fatigued.
| Set | Load | Reps |
|---|---|---|
| Bar | empty bar | 5–10 |
| 1 | 40% | 5 |
| 2 | 60% | 3 |
| 3 | 80% | 2 |
| 4 | 90% | 1 |