Calculator Tools
One Rep Max Calculator
Estimate your 1RM from a heavy set using seven proven formulas (Epley, Brzycki, Lander, Lombardi, Mayhew, O'Conner, Wathen) plus a %1RM training chart.
Common lifts
The heaviest weight you lifted with good form. Use the same units you use in the gym.
A whole number from 1 to 36. Estimates are most accurate when reps are between 1 and 10.
Training percentages
%1RM working sets
Loads are calculated from your average 1RM and rounded to the nearest 5 lb plate increment.
| %1RM | Load | Typical reps | Training goal |
|---|---|---|---|
| 100% | 260 lb | 1 | True 1RM (test only) |
| 95% | 245 lb | 2 | Max strength |
| 90% | 235 lb | 3-4 | Max strength |
| 85% | 220 lb | 5-6 | Strength + power |
| 80% | 210 lb | 7-8 | Strength + hypertrophy |
| 75% | 195 lb | 9-10 | Hypertrophy |
| 70% | 180 lb | 12 | Hypertrophy |
| 65% | 170 lb | 14-15 | Endurance + hypertrophy |
| 60% | 155 lb | 16-17 | Endurance |
| 55% | 145 lb | 18-20 | Endurance |
| 50% | 130 lb | 20+ | Warm-up / endurance |
Formulas used
- Epley: 1RM = w · (1 + r / 30)
- Brzycki: 1RM = w · 36 / (37 − r)
- Lander: 1RM = 100 · w / (101.3 − 2.67123 · r)
- Lombardi: 1RM = w · r0.1
- Mayhew et al.: 1RM = 100 · w / (52.2 + 41.9 · e−0.055·r)
- O'Conner: 1RM = w · (1 + 0.025 · r)
- Wathen: 1RM = 100 · w / (48.8 + 53.8 · e−0.075·r)
w is the weight lifted, r is the reps completed. All math runs in your browser; nothing is uploaded.
Educational tool. Rep-max formulas estimate your one rep maximum from a lighter set, but the only way to know a true 1RM is to test one safely with a spotter and proper warm-up. Talk to a qualified coach before maxing out, especially for compound barbell lifts.
How to use
- Pick a common lift preset or type the weight you lifted into the weight field. Comma or period both work as decimal separators.
- Choose lb or kg using the unit toggle. The toggle changes the labels everywhere on the page but does not convert the value.
- Type the number of clean reps you completed at that weight. Whole numbers from 1 to 36 are accepted; 1 to 10 reps gives the most reliable estimates.
- Read the average 1RM in the green result card. Every individual formula is shown below it with the year it was published and what it is known for.
- Scroll to the %1RM training table to pick working-set loads from 50 to 100 percent. Loads are rounded to the nearest plate increment for your unit.
- Click Copy summary to put the full result, every formula, and the training table on your clipboard.
About this tool
One Rep Max Calculator estimates your true 1RM from a heavy set using seven well-known formulas from strength-science literature: Epley (1985), Brzycki (1993), Lander (1985), Lombardi (1989), Mayhew et al. (1992), O'Conner (1989), and Wathen (1994). You enter the weight you lifted and the reps you completed, pick lb or kg, and every formula returns an estimated one-rep maximum side by side. The headline number is the arithmetic mean of all in-range estimates so a single odd formula cannot drag the result. Brzycki, which becomes unstable above 10 reps, is automatically excluded from the average when it is out of range and flagged in the breakdown so you can see why. The calculator also builds a percentage of 1RM training chart from 50 to 100 percent in 5 percent steps with typical rep ranges and training goals at each intensity, rounded to the nearest realistic plate increment (5 lb in pounds, 2.5 kg in kilograms) so the prescribed loads match what you can actually load on a bar. Everything runs in your browser; weights and reps are never uploaded, and there is no signup. Useful for programming working sets on 5/3/1, Texas Method, Sheiko, GZCL, RP, Westside, and any periodized template that prescribes work as a percentage of 1RM; for estimating a meet opener in powerlifting; for sizing accessory work; and for tracking strength progress between mesocycles without testing a true 1RM every time. The tool is educational and not medical advice. Test a true 1RM safely with a qualified coach, a proper warm-up, and a spotter.
Free to use. Works in your browser. No signup, no login.
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