🏋️ One-Rep Max Calculator
Enter a weight and the reps you completed to estimate your one-rep max with the Epley and Brzycki formulas — plus a full percentage table for programming your training loads.
🏋️ Estimate Your 1RM
What is a One-Rep Max Calculator?
It estimates the most weight you could lift once from a set you actually performed, without the risk of a true maximal attempt. Enter the load and reps, and it runs two trusted formulas, averages them, and shows what your working weights should be at each percentage of that max.
Strength programs are built around percentages of your 1RM — heavy triples at 90%, volume work at 70%, and so on. Having an up-to-date estimate lets you load each session precisely, track progress over time, and avoid the guesswork of picking weights by feel.
❓ Frequently Asked Questions
How does the one-rep max calculator work?
Enter the weight you lifted and how many clean reps you managed. It applies two established estimation formulas — Epley and Brzycki — averages them, and builds a table of training percentages (from 100% down to 60% of your 1RM) so you can pick the right load for any set-and-rep scheme.
What is a one-rep max?
Your one-rep max, or 1RM, is the heaviest weight you can lift for a single full repetition of an exercise. It's the standard benchmark for strength and the reference point most programs use to prescribe training loads as a percentage of that maximum.
How accurate are 1RM estimates?
Estimation formulas are most accurate with lower rep counts — roughly under 10 reps — because the relationship between reps and load stays fairly linear there. Beyond about 12–15 reps, endurance and technique start to skew the numbers, so a set of 3–6 reps gives the most reliable estimate.
Should I actually test my true one-rep max?
Maximal single-rep testing carries more injury risk and demands a proper warm-up, good technique, and ideally a spotter. Estimating from a submaximal set is safer and repeatable, which is why many lifters use a calculator like this instead of grinding out risky true-max attempts every week.