Strength calculator
One-rep max calculator
Enter a recent set and get your estimated 1RM — plus the exact weights for every training percentage. Free, instant, no sign-up.
Get a plan built around your number — the coach remembers it and adapts each week.
What is a one-rep max?
Your one-rep max (1RM) is the most weight you can lift for a single rep of an exercise. Testing a true 1RM is taxing and a little risky, so most lifters estimate it from a set they actually did — say 100 kg for 5 reps — using a formula.
How this calculator works
We average two well-established formulas. Epley: 1RM = w · (1 + reps/30). Brzycki: 1RM = w · 36 / (37 − reps). Both are accurate up to about 10 reps and drift apart above that, which is why we show both and average them. A single rep is already a max, so we return the weight as-is.
Using the % table
Most programs prescribe load as a percentage of 1RM — e.g. 5×5 at 80%, back-off sets at 70%. The table above gives you the exact weights so you can stop doing mental math between sets. Want it programmed into a full week that adapts as you get stronger? That's what the coach is for.