Open the One-Rep Max Calculator
Find your estimated one-rep max from the weight and reps you lifted, using six formulas, plus a table of training weights at every percentage of your max.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
Illustration. Open the tool for the real thing.
What is the One-Rep Max Calculator?
Your one-rep max (1RM) is the heaviest weight you could lift once with good form. Testing it directly is risky, so most lifters estimate it from a harder set of several reps. Enter the weight and the reps you completed and this calculator applies six standard formulas (Epley, Brzycki, Lombardi, O'Conner, Mayhew and Wathan), shows each one and averages them for a more stable estimate.
It also builds a percentage table so you can pick the right weight for your goal: heavy sets near 85 to 95 percent for strength, 70 to 80 percent for muscle growth and 50 to 65 percent for endurance. Works in kilograms or pounds for bench press, squat, deadlift, overhead press or any barbell lift.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Epley, Brzycki, Lombardi, O'Conner, Mayhew and Wathan side by side.
Training weights from 100% down to 50% of your max with typical reps.
Switch units instantly.
Runs in your browser.
AZRS tools are free to open and use.
It opens in your browser, so there is nothing to download.
Used for
Pick one to see how it fits.
How it compares
A plain look at this tool next to the usual alternative.
| This fitness tool | Desktop software | |
|---|---|---|
| Install | Nothing to install | Usually an app or program to install |
| Account | No signup | Depends on the product |
| Cost | Free to use | Free or paid, depends on the product |
| Where it runs | In your browser tab | On your computer |
Questions people ask
What is a 1RM?
The most weight you can lift for a single repetition with proper form.
Which formula is best?
No single formula wins for everyone, which is why the average of all six is shown.
Is it safe to test a true 1RM?
It carries injury risk. Estimating from a submaximal set is safer, and a true attempt should always use a spotter or safety bars.
Does it work for any exercise?
It is designed for barbell and dumbbell lifts, and is less meaningful for bodyweight or machine exercises.
How do I use the One-Rep Max Calculator?
1. Pick kg or lb. 2. Enter the weight you lifted. 3. Enter how many clean reps you completed. 4. Read your estimated max and the table of training weights.
More free tools
Related to the One-Rep Max Calculator.
Try the One-Rep Max Calculator now
Estimate your max lift from any set, with a training-weights table. Free to use.
Try it free