Race Weight Calculator

About this calculator

Race weight estimates the body weight at which an endurance athlete's power-to-weight ratio (and therefore performance) is optimized, calculated by working out lean body mass from current weight and body fat percentage, then adding back the weight that corresponds to a target, typically lower, body fat percentage — the logic being that lean mass stays roughly fixed in the short term while body fat is the variable that can realistically be reduced before a race.

Distance runners, cyclists and triathletes use race weight targets during a build or taper phase because carrying less non-functional body fat reduces the energy cost of moving your body over a course, especially on hills, though most coaches caution that pushing body fat too low or too fast risks losing strength and increasing injury or illness risk, so the target is meant as a guide rather than an aggressive cut.

This calculator takes your current weight, current body fat percentage and target body fat percentage, and returns the estimated race weight to aim for.