Body Composition Calculators
Estimate body fat percentage, BMI, ideal weight, and more using validated measurement methods with multi-formula comparison.
Body Fat Calculator
Estimate body fat percentage using Navy tape, Jackson-Pollock skinfold, and BMI-derived methods. Compare results from up to four validated formulas.
BMI Calculator
Calculate your Body Mass Index with WHO category classification, BMI Prime ratio, and personalised healthy weight range. Free science-based tool.
Ideal Weight Calculator
Estimate your ideal body weight using Hamwi, Devine, Robinson, and Miller formulas with WHO BMI-based range. Free side-by-side comparison.
Waist-to-Hip Ratio Calculator — WHO Risk
Calculate your waist-to-hip ratio with WHO health risk classification. Simple tape measurement tool backed by epidemiological research.
Body Surface Area Calculator — Du Bois & Mosteller
Calculate body surface area using Du Bois and Mosteller formulas with side-by-side comparison. Free BSA tool for clinical and fitness reference.
Military Body Fat Calculator — DoD Tape Test
Estimate body fat percentage using the official DoD tape-test equations with pass/fail assessment against U.S. military service standards.
BMI Category Checker
Check your BMI category with range position, healthy weight targets, BMI Prime, and Deurenberg body fat estimate. Free detailed analysis tool.
Pregnancy Weight Gain Calculator — IOM Guidelines
Estimate recommended pregnancy weight gain by trimester using IOM 2009 guidelines. Covers singleton and twin pregnancies with BMI-adjusted ranges.
FFMI Calculator
Calculate your Fat-Free Mass Index with normalised FFMI adjusted to 1.8m height. Includes natural muscular potential ceiling and category interpretation.
Waist-to-Height Ratio Calculator — 0.5 Threshold
Calculate your waist-to-height ratio with the universal 0.5 boundary threshold. Compare WHtR risk categories backed by Ashwell meta-analysis research.
Lean Body Mass Calculator — Direct & Estimated
Calculate lean body mass from body fat percentage or estimate it with the Boer 1984 formula. Includes fat mass breakdown and LBM as percentage of total.
Ponderal Index Calculator — Height-Cubed Metric
Calculate your Ponderal Index using height cubed for a more proportionate body-build metric than BMI. Useful for tall and short individuals.
Body Roundness Index Calculator — Thomas 2013
Calculate your Body Roundness Index from waist circumference and height using the Thomas 2013 eccentricity formula. Includes estimated body fat range.
How to Measure Body Fat — Complete Method Guide
Compare body fat measurement methods from tape measure to DEXA. Accuracy, cost, accessibility, and step-by-step technique for each approach.
Healthy Body Fat Percentage by Age — Ranges
Evidence-based body fat ranges by age bracket and sex. ACE categories, essential fat minimums, and why "lower" is not always healthier.
BMI Alternatives
BMI told you a number. Here are eight better metrics for body composition — what each reveals, what equipment you need, and when to use which.