Body Fat Calculator

HEADS UP

This tool is for informational use only and is not medical advice. Auburn AI is not a healthcare provider. For anything that affects your health, talk to your doctor or a qualified Canadian health professional.

Uses the US Navy tape-measure method. It is an estimate, not a substitute for a proper body-composition scan.




Tracking this over time? A reliable scale makes these numbers easier to keep current. Browse options on Amazon → (affiliate link - as an Amazon Associate Auburn AI earns from qualifying purchases)

About this tool

The Body Fat Calculator estimates your body fat percentage using simple body measurements like height, weight, neck, and waist circumference. It uses established formulas such as the U.S. Navy method to give you a reasonable approximation without expensive equipment. It is useful for anyone tracking fitness progress, adjusting diet plans, or simply wanting a clearer picture of body composition beyond what the scale shows.

Reach for this tool when BMI alone feels insufficient, since BMI cannot distinguish fat mass from muscle mass. It is particularly handy before starting a new training program, when evaluating fat loss progress over weeks or months, or when discussing health goals with a nutritionist or personal trainer.

How to use it

  1. Select your biological sex, as the calculation formulas differ between male and female.
  2. Enter your height and weight in your preferred units, either metric or imperial.
  3. Measure your waist circumference at the narrowest point and enter that value.
  4. For males, also measure your neck circumference just below the larynx.
  5. For females, add your hip circumference measured at the widest point.
  6. Click Calculate to see your estimated body fat percentage and fitness category.

Pro tips

  • Take measurements first thing in the morning before eating or drinking for the most consistent, comparable results over time.
  • Use a flexible tape measure pulled snug but not compressing skin, and measure the same spots each session to reduce variance.

FAQ

How accurate is this compared to a DEXA scan?
The Navy tape method is generally within 3 to 4 percentage points of laboratory methods for most people. It is reliable enough for tracking trends but not for clinical precision.
Why does my result differ from my smart scale reading?
Smart scales use bioelectrical impedance, which is heavily affected by hydration levels, while this tool uses body measurements, so slight differences are completely normal.

Related tools

Looking for something else? Browse browse free health and fitness calculators - all free, all in your browser.
For general informational purposes only; not professional advice. Posts may contain affiliate links. Learn more.
Scroll to Top