One Rep Max Calculator (1RM)

This page uses the Epley formula: 1RM = weight × (1 + reps ÷ 30). Ten reps with 100 kg projects an estimated 1RM of 100 × (1 + 10 ÷ 30) ≈ 133 kg. It's built from a submaximal set on purpose — you lift a manageable weight for several reps instead of loading the bar to a true single-rep maximum, which removes most of the risk of a failed heavy attempt. Switch to pounds with the unit toggle if that's how you load the bar; the formula runs in kilograms either way.

The table converts your estimated 1RM into loads at fixed percentages of that max, because strength training is typically programmed by intensity rather than by an absolute weight. Higher percentages (85–95%) pair with low reps and are associated with maximal-strength work; the middle range (65–80%) is where hypertrophy-focused training commonly sits; lighter percentages support higher-rep, more endurance-oriented work. These bands describe how training is commonly organized — they are reference points for reading the table, not a program telling you what to lift.

Epley is one of several formulas built the same way — Brzycki and Lombardi are two others — and they don't always agree; the gap between them widens as rep count climbs, because the relationship between reps and percentage of max isn't perfectly linear or identical across lifters. Accuracy is best in the 1–10 rep range and gets shakier past that, since fatigue and technique breakdown start distorting how many reps a given weight really represents. Estimates also transfer better between similar barbell lifts than to machines, bodyweight movements or highly technical lifts, where skill affects the number as much as raw strength does.

Heavy near-maximal loading involves bracing and breath-holding that raises blood pressure sharply for a moment, which is a reason anyone with a cardiovascular condition should get medical clearance before working near a true or estimated max. Beginners still building technique get more distorted estimates than experienced lifters, because form tends to change under fatigue in ways that throw off the reps-to-load relationship the formula assumes. Adolescents, anyone returning from an injury, and anyone unfamiliar with a lift's technique are generally better served working with a certified strength coach or physical therapist to build a base before approaching heavy percentages of an estimated max.

Whatever the table shows, form comes before load — a heavier weight lifted with breakdown in technique is not a useful number and raises injury risk. Warming up progressively, using a spotter for barbell lifts like the bench press or squat, and treating the first attempt at a new percentage as a check rather than a certainty all reduce that risk. A certified strength and conditioning coach can turn this estimate into an actual progression that fits your experience level, equipment and any physical limitations — something a single formula cannot do.