Body Fat Calculator
U.S. Navy body fat formula from circumference measurements.
See how it works
Watch a quick simulation of this tool in action — no file needed.
How to use Body Fat Calculator
Follow these steps — everything happens instantly in your browser.
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Step 1. Pick your biological sex.
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Step 2. Enter your height, neck circumference and waist circumference.
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Step 3. If you're female, also enter your hip circumference.
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Step 4. Read your estimated body fat percentage and category.
Why use this tool
Private by design
All processing happens locally in your browser. Open DevTools → Network and you'll see zero file uploads. Ever.
Instant
No upload wait, no queue, no server round-trip. Results appear the moment you drop a file.
Free & unlimited
No accounts, no watermarks, no daily caps. Use it as many times as you like, forever.
Works everywhere
Desktop, tablet or phone — every tool is responsive and installable as a PWA for offline use.
Frequently asked questions
Everything you might want to know about body fat calculator.
Calorie Calculator
Daily calorie needs using Mifflin-St Jeor — for loss, maintenance and gain.
Lean Body Mass Calculator
LBM from Boer, James or Hume formulas.
Ideal Weight Calculator
Four classic formulas — Devine, Hamwi, Robinson, Miller — plus frame adjustment.
Waist-to-Hip Ratio Calculator
Abdominal fat distribution and cardiovascular risk.