Health & Fitness
Body Fat Calculator
Body Fat — body Fat Calculator estimates body-fat percentage from body-circumference measurements using the U.S. This page runs that same calculation on your numbers, in your browser: no signup, no uploads, nothing stored.
Body Fat Calculator takes your sex, height, neck circumference and waist circumference and gives back your body-fat % and category, applying the US Navy tape method. It's a quick, browser-based way to estimate your body-fat percentage.
About this calculator
Get body fat right and the rest of the task gets easier. Body Fat Calculator estimates body-fat percentage from body-circumference measurements using the U.S. It matters when you want a quick screening number before deciding whether a habit, plan or measurement deserves a closer look. Using the U.S. Navy circumference method for a man with height 178 cm, neck 38 cm, waist 85 cm : body fat % = 495 ÷ (1.0324 − 0.19077 × log₁₀(85 − 38) + 0.15456 × log₁₀(178)) − 450 ≈ 16.4% . The tool above does the same computation in your browser — free, private, nothing stored.
How to use
- Select your sex so the correct formula is used.
- Enter your height and neck circumference.
- Enter your waist, and hip if you selected female.
- Press Calculate to see estimated body fat percentage.
Why use Body Fat Calculator
Fast
Calculations run in your browser. No round trip to a server.
Private
Your inputs never leave your device. Nothing is uploaded.
Free
No signup, no paywall, no ads-in-results, no watermarks.
Educational
Uses common estimation formulas for educational purposes. Results are not medical advice and should not replace professional guidance.
Mobile-ready
Optimised for phones, tablets, and desktops alike.
Transparent
Clear about formulas used and their limits, with disclaimers where they matter.
Common uses
Use it for comparing before-and-after
Use it for quick fitness reference
Body Fat in personal-training sessions
Use it when learning what a metric means
Body Fat as a general wellness guide
Use it when planning a fitness routine
Technical notes
Body Fat Calculator estimates body-fat percentage from body-circumference measurements using the U.S. Navy method.
These are general-population estimates and not a substitute for advice from a qualified clinician.
Nothing you type is uploaded — the calculation happens entirely on your device.
Worked example
Using the U.S. Navy circumference method for a man with height 178 cm, neck 38 cm, waist 85 cm: body fat % = 495 ÷ (1.0324 − 0.19077 × log₁₀(85 − 38) + 0.15456 × log₁₀(178)) − 450 ≈ 16.4%. This is an estimate; methods such as calipers or DEXA can give different figures, so use it for tracking trends rather than as a clinical measurement.
FAQ
How does the U.S. Navy method work?
It estimates body fat from log-based equations using height plus neck and waist circumference for males, adding hip circumference for females.
Why do females need a hip measurement?
Average female fat distribution differs, so the female equation includes hip circumference to improve the estimate; without it the result would be skewed.
How accurate is tape-measure body fat?
It is a rough estimate, typically within a few percentage points when measured carefully, but technique and body shape introduce error.
Does the Body Fat Calculator send my data to a server?
No. The Body Fat Calculator runs entirely in your browser — your inputs never leave your device, and nothing is uploaded or stored.