CalcKitHow to Use the Body Fat Calculator
Body Mass Index tells you about weight, but it can't tell muscle from fat. Body fat percentage is the more useful number: two people with the same BMI can have very different health profiles depending on how much of their weight is fat. This calculator uses the US Navy method, developed from circumference measurements of military personnel.
To use it, select your gender, enter your height, weight, neck and waist measurements (plus hip for women), then press Calculate Body Fat. You'll get your estimated body fat percentage, a category โ essential, athletes, fitness, average or obese โ and a split of fat mass versus lean mass.
The formulas are: for men, 86.010 ร log10(waist โ neck) โ 70.041 ร log10(height) + 36.76; for women, 163.205 ร log10(waist + hip โ neck) โ 97.684 ร log10(height) โ 78.387. Measurements go in as inches internally, so enter centimetres and the calculator converts automatically.
Typical healthy ranges are about 10โ20% for men and 18โ28% for women, with athletes lower. This is an estimate โ DEXA scans and hydrostatic weighing are more accurate but expensive. Measure consistently (same time of day, same tape position) and track the trend rather than obsessing over a single reading. Pair it with our BMI Calculator and Calorie Calculator for a full fitness plan.