Free calculators for BMI, body fat, lean mass, waist ratios and other measures of body composition. Each one shows its formula and sources, and nothing you enter is stored.
Body Composition
Weight and BMI
BMI Calculator
Use this BMI calculator to calculate your body mass index and see where your weight falls on the standard BMI scale.
Ideal Weight Calculator
Use this ideal weight calculator to estimate your ideal body weight from your height and sex using a clinical formula.
Adjusted Body Weight Calculator
Use this adjusted body weight calculator to estimate a clinical reference weight used for dosing above ideal weight.
Body Surface Area Calculator
Use this body surface area calculator to calculate your BSA from your height and weight using the Mosteller formula.
Reverse BMI Calculator
Use this reverse BMI calculator to find the weight needed to reach a specific target BMI at your height.
Weight Loss Percentage Calculator
Use this weight loss percentage calculator to see what percentage of your starting body weight you've lost.
GLP-1 Weight Loss Calculator
Use this GLP-1 weight loss calculator to see what the average result in the main clinical trials would mean for your starting weight.
Weight Cut Calculator
Use this weight cut calculator to plan how much weight to lose before weigh-in, and how much can come off safely before fight week.
Ponderal Index Calculator
Use this ponderal index calculator to find an adult's ponderal index in kg/m³ or a newborn's Rohrer's index, with gestational age context for babies.
Body Fat and Muscle
Body Fat Calculator
Use this body fat calculator to estimate your body fat percentage from tape measurements using the U.S. Navy method.
Lean Body Mass Calculator
Use this lean body mass calculator to estimate your LBM, the weight of your body excluding fat mass.
FFMI Calculator
Use this FFMI calculator to calculate your fat-free mass index, a height-adjusted measure of muscularity.
Army Body Fat Calculator
Use this Army body fat calculator to check the 2026 waist-to-height standard (under 0.55) and see your former one-site tape test estimate.
Skeletal Muscle Mass Calculator
Use this skeletal muscle mass calculator to estimate your total muscle mass from height, weight, age, and sex.
Visceral Fat Calculator
Use this visceral fat calculator to estimate your visceral fat risk from your waist and waist-to-height ratio.
Relative Fat Mass (RFM) Calculator
Use this Relative Fat Mass (RFM) calculator to estimate your body fat percentage from your height and waist, and compare it with the obesity cut-offs.
Skinfold Body Fat Calculator
Use this skinfold body fat calculator to estimate your body fat percentage from caliper readings, with the Jackson-Pollock or Durnin-Womersley method.
Shape and Measurements
Waist-to-Height Ratio Calculator
Use this waist-to-height ratio calculator to compare your waist measurement with your height and assess body fat distribution.
Body Frame Size Calculator
Use this body frame size calculator to find whether you have a small, medium, or large frame from your wrist circumference and height.
Body Roundness Index (BRI) Calculator
Use this body roundness index calculator to estimate your body shape from waist circumference and height.
Body Type Calculator
Use this body type calculator to find your body shape (hourglass, spoon, pear, rectangle and more) from your bust, waist, high hip and hip measurements.
Waist-to-Hip Ratio Calculator
Use this waist-to-hip ratio calculator to compare your waist and hip measurements and assess body fat distribution.
Shoulder to Waist Ratio Calculator
Use this shoulder to waist ratio calculator to divide your shoulder size by your waist size and see how you compare with the 1.618 golden ratio.
Beighton Score Calculator
Use this Beighton score calculator to add up your 9-point hypermobility score and compare it with the cutoff for your age group.
ABSI Calculator
Use this ABSI calculator to find your A Body Shape Index, a waist measure adjusted for your height and weight that is linked to mortality risk.
Children and Height
Kids BMI Calculator
Use this kids BMI calculator to find your child’s BMI-for-age percentile and category, including severe obesity, from the CDC growth charts (ages 2 to 19).
Child Growth Percentile Calculator
Use this child growth percentile calculator to find your child's height-for-age and weight-for-age percentiles.
Child Height Predictor
Use this child height predictor to estimate how tall your child will be as an adult, from parents' heights and your child's current height.
Height Percentile Calculator
Use this height percentile calculator to see how your height compares with US adults of your age and sex, using measured CDC survey data.
Baby Weight Percentile Calculator
Use this baby weight percentile calculator to see where your baby's weight sits on the WHO growth charts, by exact age in days, from birth to age 2.
Head Circumference Percentile Calculator
Use this head circumference percentile calculator to see where your child's head size sits on the WHO growth charts, by exact age, from birth to age 5.