One Rep Max Calculator
Enter a weight and rep count from a real set. Get five published 1RM estimates, the average, and a full training-percentage table rounded to plates you can actually load.
Epley (default)
216
lb
Brzycki
208
lb
Lombardi
217
lb
O'Conner
208
lb
Wathan
216
lb
Average of all five: 213 lb
1RM percentage table (from your Epley estimate)
| % of 1RM | Weight (lb) | Est. reps |
|---|---|---|
| 50% | 110 | 30 |
| 55% | 120 | 25 |
| 60% | 130 | 20 |
| 65% | 140 | 16 |
| 70% | 150 | 13 |
| 75% | 160 | 10 |
| 80% | 175 | 8 |
| 85% | 185 | 5 |
| 90% | 195 | 3 |
| 95% | 205 | 2 |
| 100% | 215 | 1 |
Weights rounded to the nearest 5 lb — a real, loadable plate increment, not a raw decimal.
How it's calculated
Five published formulas, each estimating what a single all-out rep would have been from your submaximal set of w weight x r reps:
Epley (default): 1RM = w × (1 + r / 30)
Brzycki: 1RM = w / (1.0278 − 0.0278 × r)
Lombardi: 1RM = w × r0.10
O'Conner: 1RM = w × (1 + 0.025 × r)
Wathan: 1RM = 100w / (48.8 + 53.8 × e−0.075r)
At exactly 1 rep, every formula returns the weight you lifted unchanged -- a single rep at a weight already is a 1RM, so there's nothing to estimate.
Worked example: 185 lb × 5 reps
| Formula | Math | Result |
|---|---|---|
| Epley | 185 × (1 + 5/30) = 185 × 1.1667 | 216 lb |
| Brzycki | 185 / (1.0278 − 0.139) | 208 lb |
| Lombardi | 185 × 5^0.10 | 217 lb |
| O'Conner | 185 × (1 + 0.125) | 208 lb |
| Wathan | 100×185 / (48.8 + 53.8×e⁻⁰·³⁷⁵) | 216 lb |
| Average of all five | 213 lb |
Enter 185 and 5 into the calculator above and every number matches -- that's the same code path, not a separate example.
Pick your lift
The calculator above works for any barbell lift. These pages run the same five formulas with lift-specific notes and a table of estimated 1RM by common set/rep pairs (5×5, 3×8, and more):
Frequently Asked Questions
Which formula should I actually trust?
Epley is this site's default -- it's the formula most strength coaches and lifting apps reach for first, and it tracks the five-formula average closely under about 10 reps. But no formula is exact: treat the number as a planning estimate, not a number to attempt cold without a spotter.
Why do the five formulas disagree?
Each one was fit to a different dataset with a different shape -- Epley and O'Conner are straight lines, Brzycki curves, Lombardi is a power law, Wathan is an exponential decay. They agree closely at low reps because that's where all the underlying data was densest, and spread apart above about 8-10 reps because that's where it thins out.
Is a calculated 1RM the same as a tested 1RM?
No. This is an estimate from a submaximal set. A tested max also depends on the day, your warm-up, your nervous system, and technique under a truly maximal load -- none of which a formula can see. Use the estimate to plan percentages, not as a number to chase on a first attempt.
Why cap reps at 12?
Every formula here was built from sets in roughly the 1-10 rep range. Past about 10-12 reps the estimate drifts further from a tested max with every additional rep, so the calculator stops taking rep counts past 12 rather than return a number that looks precise but isn't.
What does the percentage table use as "my 1RM"?
Your Epley estimate, since that's the site default. If you prefer one of the other four, take that number to the plate calculator directly -- the percentage math (weight x percent, rounded to a loadable plate) works the same regardless of which formula produced the 1RM.
Every number on this page is an estimate, not a prescription. Test a true max only with a qualified spotter. See Terms.