Free strength calculator · lb & kg
One rep max calculator
Enter a weight and how many reps you did. You get your estimated 1RM, the loads for every training percentage, and the exact plates to put on the bar.
Estimated one rep max
214lb
Range across 7 formulas: 208–220 lb
Percent of 1RM
| % | Load | Reps | Use |
|---|---|---|---|
| 100% | 215 lb | 1 | Max attempt |
| 95% | 205 lb | 2 | Peaking, heavy singles |
| 90% | 190 lb | 3–4 | Max strength |
| 85% | 180 lb | 5–6 | Strength |
| 80% | 170 lb | 7–8 | Strength / hypertrophy |
| 75% | 160 lb | 9–10 | Hypertrophy |
| 70% | 150 lb | 11–12 | Hypertrophy |
| 65% | 140 lb | 13–15 | Volume, technique |
| 60% | 130 lb | 15–20 | Warm-up, endurance |
| 50% | 105 lb | 20+ | Warm-up |
Rep maxes
| Reps | Estimated max |
|---|---|
| 1RM | 215 lb |
| 2RM | 205 lb |
| 3RM | 200 lb |
| 4RM | 190 lb |
| 5RM | 185 lb |
| 6RM | 180 lb |
| 7RM | 175 lb |
| 8RM | 170 lb |
| 9RM | 165 lb |
| 10RM | 160 lb |
| 11RM | 155 lb |
| 12RM | 150 lb |
By formula
| Formula | 1RM |
|---|---|
| Epley | 216 lb |
| Brzycki | 208 lb |
| Lombardi | 217 lb |
| Lander | 210 lb |
| O'Conner | 208 lb |
| Mayhew | 220 lb |
| Wathen | 216 lb |
Headline number = average of all seven. How the formulas differ
How to use the calculator
- Pick a recent hard set. The heaviest set you did for 1–10 reps, finished with good form.
- Enter the weight and reps. Switch between pounds and kilograms at any time — the numbers convert for you.
- Read your numbers. The big figure is your estimated 1RM. The tables give you working weights for any percentage or rep target, rounded to loads you can actually build with standard plates.
What is a one rep max?
Your one rep max (1RM) is the most weight you can lift for a single, full repetition with good technique. Coaches use it as a yardstick: most strength programs prescribe work as a percentage of 1RM — three sets of five at 80%, for example — so knowing your max turns a program into real numbers on the bar.
Testing a true max is tiring and carries more risk than normal training. An estimated 1RM gets you a usable number from a set you were going to do anyway.
How the estimate works
Researchers have fitted several equations to the relationship between reps and load. Each one takes your weight and reps and predicts what you could lift once. This calculator runs seven of them — Epley, Brzycki, Lombardi, Lander, O'Conner, Mayhew and Wathen — and shows the average as your headline number, with the spread between them as a range.
At 1–5 reps the formulas agree closely. Past 10 reps they diverge, because endurance starts to matter as much as strength. That's why the most reliable estimate comes from a heavy set in the 2–6 rep range.
Using your 1RM in training
Most programs work in zones: heavy singles and doubles at 90% and above, strength work around 80–90%, muscle-building sets at 65–80%. The Percent of 1RM table above turns those zones into loads. The Rep maxes table runs the other way and estimates what you could do for 3, 5 or 8 reps.
If you train with RPE (rate of perceived exertion) instead of fixed percentages, use the RPE calculator, which estimates your max from how hard a set felt.
Lift-specific calculators
Questions lifters ask
How accurate is a one rep max calculator?
For a hard set of 2–6 reps, the estimate is usually within about 5% of a tested max. Accuracy drops as reps go up: above 10 reps the formulas start to disagree, which is why the calculator shows a range as well as the average.
Which set should I enter?
Your heaviest recent set taken close to failure — ideally one or two reps short of failing, with good form. A warm-up set or an easy set of 10 will underestimate your max.
Which 1RM formula is best?
No single formula wins for every lifter or lift. Epley and Brzycki are the most widely used and agree closely at low reps. Averaging seven formulas smooths out their individual biases. See 1RM formulas explained.
Does it work for any exercise?
It works best for barbell compound lifts — bench press, squat, deadlift, overhead press. For machines, dumbbells and isolation exercises the estimate is rougher, because the formulas were built from free-weight data.
How often should I recalculate my 1RM?
Every 4–8 weeks, or at the end of a training block. Because the calculator works from a normal hard set, you can update your numbers without a risky max-out session.
Is it safe to test a true one rep max?
It can be, with a proper warm-up, a spotter or safety bars and solid technique. Beginners usually get more from an estimated max. Read how to test your 1RM safely first.
These numbers are estimates for training purposes, not medical advice. If you have an injury or a health condition, talk to a qualified professional before lifting heavy.