One Rep Max Calculator
Estimate your 1RM from any set using the Epley, Brzycki or Lombardi formula, with a full percentage table for programming your training loads. Free, instant, and runs in your browser.
Updated
One rep max (1RM)
The unit does not matter — the result comes back in whatever you enter.
Clean reps to near-failure. Accuracy drops sharply above 10.
Estimated 1RM
215.8
- 95% training load
- 205.0
- 90% training load
- 194.3
- 85% training load
- 183.5
- 80% training load
- 172.7
- 75% training load
- 161.9
- 70% training load
- 151.1
- 65% training load
- 140.3
- 60% training load
- 129.5
How this is calculated
Epley: 1RM = weight × (1 + reps / 30) · Brzycki: weight × 36 / (37 − reps) · Lombardi: weight × reps^0.1
- An estimate, not a target. These formulas are fitted curves, and all three drift apart above about 10 reps — below 6 they agree closely.
- Assumes reps taken close to failure with consistent form. Reps left in the tank make the estimate low.
- A single rep is by definition your 1RM, so at 1 rep every formula returns the weight you entered.
- Never attempt a true 1RM alone or without warming up. Percentage loads are the safer way to use this number.
Frequently Asked Questions
Which 1RM formula is the most accurate?
None of them is accurate in the way a tested max is — they are curves fitted to population data. Below about 6 reps all three agree closely, so the choice barely matters. Above 10 reps they diverge sharply, with Brzycki reading lowest and Epley highest. If you are estimating from a set of 3 to 5, use any of them; if you are estimating from a set of 15, treat the number as a rough ceiling.
Why does 1 rep return exactly the weight I entered?
Because a single rep taken to failure is your one rep max by definition. The raw Epley formula actually returns 3.3% more than the weight at one rep, which is a known artefact of the curve, so this calculator pins the one-rep case to the weight you lifted.
What are the percentage loads for?
Most strength programmes prescribe work as a percentage of 1RM — 5×5 at 80%, speed work at 60%, a heavy single at 95%. The table converts your estimate into those loads so you do not have to do the arithmetic between sets.
Does it matter whether I enter pounds or kilograms?
No. Every formula scales linearly with weight, so the result comes back in whatever unit you put in. Just do not mix them.
Should I actually test my one rep max?
Rarely, and never without a full warm-up and a spotter. A true max attempt carries real injury risk and taxes recovery for days. For most lifters the estimate plus percentage loads is more useful than the test, which is exactly why these formulas exist.
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About One Rep Max Calculator
One Rep Max Calculator is a free, browser-based tool in our Calculator Tools collection. Everything runs locally on your device — no uploads, no sign-up, and your data stays private.