One-rep max calculator
You don’t need to grind out a true max to know your strength. Take any hard set — the weight and the reps you got — and this calculator estimates your one-rep max two ways, with the Epley and Brzycki formulas, then turns it into a table of training percentages.
AION
I can estimate your one-rep max from any hard set — no need to actually grind a single. Two numbers.
AION
First — pounds and inches, or kilos and centimeters?
Common questions
- How accurate are 1RM formulas?
- Good enough to program with, especially from sets of ten reps or fewer. The further your rep count gets from a true max effort, the wider the error — a set of 15 predicts far less precisely than a set of 5.
- Why do Epley and Brzycki give different numbers?
- They fit different curves to the same question. The two agree exactly at 10 reps and drift apart on either side — Epley reads higher above 10 reps, Brzycki higher below. Showing both gives you an honest range.
- Do I need to actually test my one-rep max?
- For programming, no. The estimate exists so you can set training percentages without the risk and fatigue of a true max attempt. Testing is for meets and milestones, not for math.
- What are the percentages for?
- Programs prescribe weights as a share of your 1RM — heavy strength work typically lives around 80–90%+, higher-rep muscle-building work lower. The table turns your estimate into loadable numbers.