Enter a weight and the reps you did to estimate your one-rep max, with a percentage table for training loads.
How this calculator arrives at its answer
Your one-rep max (1RM) is the most you can lift for a single rep. Instead of testing it directly, this calculator estimates it from a set you’ve done using the Epley and Brzycki formulas.
The percentage table then shows training loads — useful for programming strength work at, say, 80% of your max.
Getting your answer
- Enter the weight you lifted.
- Enter the number of reps you completed.
- Read the estimated 1RM and the percentage table.
The maths behind it
Epley 1RM = weight × (1 + reps ÷ 30)
Brzycki 1RM = weight × 36 ÷ (37 − reps)
Worked example
On the values this calculator opens with, the estimated 1RM is 116.7. Alongside it, Brzycki est. comes out at 112.5. Change any field and every figure updates as you type.
Common questions
How accurate is a 1RM estimate?
It’s most accurate for sets under about 10 reps. Beyond that, estimates drift, so use lower-rep sets for the best guess.
Why do formulas differ?
Each was fitted to different data. Epley and Brzycki agree closely at low reps and diverge as reps rise — seeing both gives a useful range.
Should I test my true 1RM?
Maxing out carries injury risk, especially without a spotter and good form. Estimates are a safer way to gauge progress.