Estimate your 1RM from any set
Enter the weight and reps, plus RPE if you track it, to get an estimated one-rep max. With RPE, the reps you had left in the tank count too, so 10 reps at RPE 7 is treated like a 13-rep max.
Know your one-rep max.
Enter the weight and reps you lifted, add RPE if you use it, and get an estimated 1RM in seconds. Save your results by exercise to keep track of your lifts.
Everything a 1RM calculator should do.
Quick to use between sets, clear about how the numbers are calculated, and free for all the core features.
Rep maxes and percentages
See the estimated weight for 2 reps and up, each shown as a percentage of your 1RM. Handy for planning your working sets.
History for every exercise
Save results to your history by exercise, add your own custom exercises, and edit or backdate records. Export your history as CSV anytime.
Formulas you can check
Your estimate is the average of the Epley, Brzycki (up to 12 reps), Wathan, and Mayhew formulas. The app lists each one so you can see how the number is calculated.
kg or lbs. Light or dark.
Switch between kilograms and pounds, use dark mode, and use the app in 9 languages: English, Japanese, Spanish, Portuguese, French, German, Italian, Russian, and Korean.
Frequently Asked Questions
Have another question? Email us.
What is a one-rep max (1RM)?
Your 1RM is the heaviest weight you can lift for a single repetition of an exercise with good form. Many training programs set working weights as a percentage of it.
What is RPE?
RPE (Rating of Perceived Exertion) rates how hard a set felt, usually on a scale of 1 to 10. In lifting, it mostly means how many more reps you could have done: RPE 10 is a maximal effort, RPE 9 means one more rep was left, RPE 8 means two, and so on. If you enter RPE, the app adds those reps in reserve before estimating your 1RM.
How accurate is the estimate?
It is an estimate, not a tested max. The app averages several published formulas (Epley, Brzycki up to 12 reps, Wathan, and Mayhew), which agree most closely for low-rep sets. The more reps you enter, the less reliable the estimate becomes, and your tested max may be higher or lower depending on the exercise, your technique, and your training experience.
Is the app free?
Yes. The calculator, rep max and percentage table, history, custom exercises, and CSV export are free. Pro is an optional in-app purchase that adds a 1RM progress chart and a table of your best recorded sets, and removes promotional banners.
Do I need an account?
No. There is no sign-up. Your history is saved on your device.
Can I export my data?
Yes. You can export your saved history as a CSV file from Settings and open it in any spreadsheet app.
Is it available on Android?
Yes. It is available for iPhone on the App Store and for Android on Google Play.
Find your 1RM on your next set.
Download 1RM Calculator for free on iPhone and Android.