One-Rep Max Calculator
Enter a set you actually did — weight and reps — and get your estimated one-rep max from the Brzycki formula. Reps are capped at ten, because an estimate built on a longer set isn't one you should trust.
Rounds to 115.0 kg loaded on a bar.
How the number is computed
Brzycki estimates your one-rep max as weight × 36 ÷ (37 − reps). Worked out for a set of 102.5 kg × 5:
A true single is its own estimate — enter one rep and the formula steps aside, returning the weight you lifted. Enter more than ten reps and the count is held at ten before the division runs.
Why the estimate stops at ten reps
Most one-rep-max calculators will take a set of twenty reps and hand you a number. The math still runs — the number it returns is fiction. Every rep-based 1RM formula is a curve fit to real lifting data, and that data thins out fast above a handful of reps. Brzycki holds up well through about five reps and stays usable to ten. Past that, the same equation overshoots: a twenty-rep set measures work capacity and grit as much as strength, and reading it as a max produces a top-end number no lifter should load a bar to.
So the estimate caps the rep count at ten. Enter a fifteen- or twenty-rep set and you still get an answer — figured at ten, with a note that the cap fired. The number stops climbing because the confidence behind it already has.
This matters because the 1RM is not the end of the calculation. In Sterka it seeds the training max, the load bands, and the whole four-week wave. An inflated max doesn't stay a harmless figure on a screen; it becomes a working weight you're asked to hit for reps, then miss. Undershooting costs you a little intensity for one session. Overshooting costs you the session. The cap is which side of that trade the engine takes, on purpose.
For the cleanest estimate, give it a heavy set of three to six reps with a rep or two left in reserve. That is the range the formula was built for — and the range your training runs in anyway.
Sterka turns this estimate into loads, sets, and rest for every session — then recalibrates it as you lift.
Join the WaitlistThis is an estimate from one set — a calculated number, not a max to walk up to cold. It's the engine's math on your input, not a training plan. Consult a clinician before starting a new program.