All calculators
Free, no sign up, and each one names the formula it uses and the paper it comes from. Everything runs in your browser; nothing you type is sent anywhere.
Body fat percentage
Three published methods, and it tells you which one your measurements allow.
Waist to height ratio
The simplest check of where your weight sits. Keep it under half your height.
Waist circumference
The tape on its own, against the two thresholds everyone quotes or the IDF line for South Asian and Chinese adults.
Calorie deficit
Pick a pace, see what to eat and where it leads, on a line that slows as you get lighter.
Healthy weight range
The range of weights inside the healthy BMI band at your height. A range, not a number.
Child and teen BMI
Ages 5 to 19 placed on the WHO growth curves for their exact age, never against adult cut points.
US Navy body fat
The circumference method in full, with the equation and where to hold the tape.
Lean body mass
Everything you are made of except fat, by Boer, James and Hume side by side.
Body Roundness Index
Your waist and height, read through a different equation. Thomas and colleagues, 2013.
Body Shape Index (ABSI)
How much waist you carry for your size, against adults of your age and sex. Krakauer and Krakauer, 2012.
On your phone it also remembers last time
The app runs the same formulas, keeps your past readings so it can tell you what changed, handles more than one person, and checks children against growth curves rather than adult cut points.
Not sure which measurement you need, or how to take it properly?Read the guides.
Free, no account, and it works offline. 100,000+ downloads on Google Play.
This is not medical advice. Body Numbers is a calculator. It does not diagnose, treat or monitor any condition, and no number it produces should replace a conversation with a doctor or a dietitian. If a result worries you, or if you are pregnant, unwell, or under eighteen, speak to a health professional.
