Body Fat Calculator

How to use Body Fat Calculator

1. Open Body Fat Calculator in your browser — it loads instantly and works offline once cached.
2. Enter your values in the input fields. Every field is labelled so you know exactly what to type.
3. The result updates automatically as you type — there is no "submit" round-trip to a server.
4. Adjust any input to compare scenarios and see how the outcome changes in real time.
5. Copy or note the result. Nothing you enter is stored or sent anywhere.

Why use Body Fat Calculator?

• 100% free with no limits, no sign-up and no watermarks.
• Private by design — your data are processed in your browser and never uploaded to a server.
• Fast and lightweight, with instant results even on a phone or a slow connection.
• Works everywhere — any modern browser on Windows, macOS, Linux, Android or iOS.
• Part of a full health & fitness suite, so related body fat tasks are one click away.

What people use Body Fat Calculator for

• Estimating body fat percentage from tape measurements.
• Tracking composition change when scale weight is not moving.
• Getting a more informative figure than BMI alone.

Body Fat Calculator: limits and things worth knowing

• Tape-based methods such as the US Navy formula use circumference measurements and are estimates with typical error of ±3-4 percentage points against a DEXA scan.
• Consistency matters more than absolute accuracy: measure at the same points, at the same time of day, under the same conditions, and track the trend rather than any single reading.
• Essential fat is roughly 3-5% for men and 10-13% for women. Below those levels carries real health consequences, including hormonal disruption.
• Bioimpedance scales are strongly affected by hydration and can swing several percentage points within a day.
• General information only, not medical advice.

Is it private and secure?

Your privacy is built in. Body Fat Calculator runs completely on your device, so whatever you enter stays in your browser and is never transmitted, logged or stored on any server.

Network activity: none. Nothing is sent and nothing is fetched. This tool makes no network request at all once the page has loaded — which is why it keeps working if your connection drops.

You do not have to take that on trust — our privacy proof page publishes the Content-Security-Policy that enforces it, lists every third party it permits, and shows how to verify the whole claim yourself.

Learn more

Why Browser-Based Tools Are Safer for Your Files — Most online converters upload your files to a server. Client-side tools don't. Here's why that difference matters for privacy.