Calculate your one-rep max

Your one-rep max is the heaviest weight you could lift for a single, full rep of an exercise. It matters because most programming — what weight to use for a given set of reps, how heavy a top set should feel — is easier to plan as a percentage of that number than as a guess from scratch each session.

You don't need to test it often — most lifters are better off estimating it from a hard set of 3-5 reps (like this calculator does) rather than actually maxing out, especially without a spotter. A true 1RM attempt carries more injury risk and more nervous-system fatigue than it's worth for most training goals. If you do want to test it directly, do it on a lift you're technically solid on, with a spotter or safety bars, after a proper warm-up — and skip it entirely if you're new to the movement.

Your 1RM is the actual (or estimated) ceiling — the most you could lift once. A training max is a deliberately conservative number, often 85-90% of your 1RM, that programs are built around instead. Basing weeks of training on a slightly lower number leaves room to hit reps with good form and still have something left, rather than grinding against your true limit every session.

Epley, Brzycki, and Lombardi all estimate 1RM from a lighter set, but they extrapolate slightly differently — Epley tends to run a little higher than Brzycki in the 3-10 rep range, and Lombardi sits close to both. In that 2-10 rep window they're all reasonably accurate (within a few percent of a true tested max for most lifters). Outside that range, all three get shakier, which is why very high-rep sets aren't a reliable way to estimate a max.

Bodyweight matters because a heavier lifter can generally move more absolute weight — comparing raw kilos across bodyweights isn't a fair comparison, so standards are expressed relative to bodyweight instead. Sex matters because of differences in average muscle mass and body composition, which is why treating a men's strength chart as unisex quietly under-rates most women's actual progress. Age matters because strength typically peaks in the late 20s to mid-30s and declines gradually after — the classification here adjusts for that instead of comparing a 55-year-old against a standard built for 25-year-olds.

Strength-focused work tends to sit heavier and lower-rep — often 80-95% of 1RM for 1-5 reps — because getting better at near-maximal loads is the actual goal. Hypertrophy work usually sits lower, around 65-80%, for more total reps, since muscle growth responds more to total volume under enough tension than to how close you are to your ceiling. Your 1RM is the anchor either way — it's what turns "lift heavy" or "do more volume" into an actual number on the bar.

Match the percentage to what a block of training calls for: heavier percentages (85%+) for low-rep strength work, mid-range (70-85%) for most everyday working sets, lighter (65-70%) for volume, technique work, or a deload. As your estimated 1RM goes up, recalculate — the table is only as accurate as the number it's built from, so it's worth updating every few weeks of consistent training rather than working off a number from months ago.