Strength
One Rep Max Calculator
Updated 1 Nov 2026 · Source: Epley, Brzycki and Lombardi formulas ↗
Enter the weight you lifted and how many clean reps you finished, and the calculator estimates the heaviest single you could lift today, plus a percent chart built from that number.
Worked example
- Epley: 185 × (1 + 5 ÷ 30) = 215.8 lb
- Brzycki: 185 × 36 ÷ (37 − 5) = 208.1 lb
- Lombardi: 185 × 5^0.10 = 217.3 lb
- Average of the three: (215.8 + 208.1 + 217.3) ÷ 3 = 213.8, shown as 214 lb
Percent chart for a 214 lb max
| % of max | Weight (lb) | Reps you might get |
|---|---|---|
| 100% | 214 | 1 |
| 95% | 203 | about 2 |
| 90% | 192 | about 3 |
| 85% | 182 | about 5 |
| 80% | 171 | about 7 |
| 75% | 160 | about 10 |
| 70% | 150 | about 12 |
| 65% | 139 | about 14 |
| 60% | 128 | about 16 |
| 55% | 118 | about 19 |
| 50% | 107 | about 21 |
How the estimate works
Every rep max formula assumes the same thing: the more reps you can do with a weight, the further that weight sits below your max. The formulas differ in how fast they think strength drops as reps go up.
We average three of them (Epley, Brzycki and Lombardi) for the headline number and show all seven as a range, so you can see how much they agree. With the default set of 185 lb for 5 reps, the average comes out at about 214 lb (97 kg). The full list with authors and years is on the 1RM formula page.
Choosing a set worth entering
The estimate is only as good as the set behind it. Use a set taken close to failure, where one more clean rep would not have happened. A set you stopped early with plenty left in the tank makes your max look lower than it is.
Lower rep sets predict better. Studies that compared formulas with real tested maxes found them more accurate when the set had fewer than 10 reps, and one found a 5 rep max gave the closest prediction. A heavy set of 3 to 8 reps is a good target.
- Warm up first, then do one hard set at a weight you can lift 3 to 8 times.
- Count only full reps with the same depth or range you always use.
- Enter the set the day you do it, not one from weeks ago.
Why your real max may differ
A formula cannot see how you train. Someone who mostly does sets of 10 may get more reps at a given percentage than someone who mostly does singles, so the same set can point to different maxes. For some people the estimate is off by 10% or more.
The lift matters too. In one study the formulas tracked bench press and squat maxes closely, while all of them came in low on the deadlift. Treat the result as a planning number, not a promise.
Putting the number to work
Most programs prescribe loads as a share of your max. The percent chart under the calculator turns your estimate into weights for 95% down to 50%, with a rough rep count for each. The rep max chart does the reverse when you start from a rep target.
If you choose to try a heavy single, the calculator suggests 95% of the estimate as a first attempt. Use a spotter or set safety bars for any near-max lift in a rack.
When to update it
Your max moves as you train, so refresh it from a new hard set every few weeks instead of testing a true single. Comparing those estimates over time is a simple way to check whether your progressive overload plan is working.
Related pages
One Rep Max Formula, Rep Max Chart, How Many Sets and Reps, Bench Press Calculator
Questions
Is a 5 rep set good for estimating a max?
Yes. Sets of about 3 to 8 reps taken close to failure give steadier estimates than sets of 12 or more, and a 5 rep max did best in one comparison study.
Why does a set of 1 show the same weight?
One rep with a weight already is a max for that day, so the calculator returns the weight itself instead of running a formula.
Should I enter my weight in lb or kg?
Either one. Pick the unit you lifted in and the results, percent chart and rounding follow it (5 lb or 2.5 kg steps).
Can I use this for machines and dumbbells?
You can, but the formulas were built mostly on barbell lifts. Results for machines vary with the machine, so compare a machine only with itself.
How we calculate: every formula, with its author and year, is on our method page; data sources and their licenses are on sources.
gymnical.com gives estimates from published formulas and public data. It is not medical advice and not a training prescription. Last reviewed November 2026.