YPTTools
1RM calculator
Enter the weight and reps from your set to get an estimated one-rep max – plus working weights as percentages of your 1RM.
Weights by percentage of 1RM
| % 1RM | Weight | ≈ reps |
|---|
How the calculator works
What is a 1RM
Your 1RM is the heaviest weight you can lift for one rep with good form. Estimating it from a heavy set of several reps is safer than testing a true max and is enough to plan your training.
Epley – the same as the app
1RM = weight × (1 + reps / 30). YPT uses this formula on every logged set, so the numbers match the charts in the app. For a single rep it comes out 3% above the weight lifted.
Brzycki for comparison
1RM = weight × 36 / (37 − reps). For low reps it gives results similar to Epley; above 10 reps they diverge. That's why the calculator shows both.
RPE and reps in reserve
If you enter RPE, the calculator adds the reps you had left in the tank (10 − RPE). A set of 5 at RPE 8 is calculated as 7 reps to failure. In the app, 1RM is calculated from weight and reps only.
Most accurate up to 10 reps
The more reps, the more endurance affects the estimate. Use a set of 3–8 reps to estimate your max.
YPT does this automatically
YPT estimates your 1RM from every set you log and shows it on the exercise's progress chart – along with PRs by rep count and RPE. The AI coach uses your numbers to set the load for your next sessions.
Strength training & powerlifting → How the AI coach works →
Free · no ads · iPhone & Android
FAQ
How accurate is an estimated 1RM?
It's an estimate – your true max can differ depending on the exercise, technique and your endurance. It's most reliable from a set of 3–8 reps with good form.
Should I test my true max?
You don't need to for planning your training. If you do, only with experience, good technique, a proper warm-up and a spotter or safeties.
Why do Epley and Brzycki differ?
They are two different empirical formulas. At low reps they give almost the same number; they diverge as reps go up.
Does the calculator store my data?
No. Everything is calculated in your browser and nothing is sent anywhere.
The calculator is for guidance only. If you have health concerns or are coming back from an injury, talk to a doctor before heavy training.