Best Free Body Fat Calculator Online in 2026 — Navy Formula, No Sign-up
Why the Navy Formula Is the Best Free Method
The Navy body fat formula requires only a tape measure and three measurements (waist, neck, height for men; waist, neck, hip, height for women). It’s validated against DEXA in multiple studies, used by the US military for fitness assessments, and free. No equipment to buy, no app to install.
How to Take the Required Measurements
Neck: measure around the neck just below the larynx (Adam’s apple), slightly angled downward. Waist: measure at the narrowest point, usually just above the navel. Hip (women only): measure at the widest point of the hips/buttocks. All measurements should be taken while standing, tape snug but not compressing.
Interpreting Your Result
The calculator shows your body fat percentage and places it in a category (essential/athletic/fitness/acceptable/obese) based on your age and gender. It also shows how much of your total weight is fat mass versus lean mass — useful for tracking changes over time.
Frequently Asked Questions
Calculate body fat now
Open Body Fat Calculator — waist, neck, height — instant result, no sign-up.
Open Body Fat Calculator