Body composition · Free calculator

Body Fat Percentage Calculator

Estimate body fat percentage with the US Navy tape method from height, neck, waist, and hip measurements — plus lean mass and category.

Short answer

Body Fat Percentage Calculator

17.51 : 1Estimated body fat

Lean mass of 148.5 lb is the number to protect while dieting. If body fat falls but lean mass falls with it, the deficit is too steep or protein is too low. The tape method carries roughly ±3% error versus DEXA, so track the trend across weeks rather than chasing one reading.

How it's calculated: 17.5% — Fitness band. About 31.5 lb fat and 148.5 lb lean mass. Adjust the inputs below to recalculate for your own numbers.

Disclaimer: Educational estimate only — not medical advice, diagnosis, or treatment. Population formulas do not account for your individual physiology, medications, or medical history. Discuss any health decision with a licensed clinician, and seek immediate care for urgent symptoms.

New here? Watch it work in 2 seconds — then tweak it for you.
1
70
34
15
0
180
Try it like this

Tap a scenario to load realistic numbers, then tweak the sliders.

Formula used

US Navy circumference method

The Navy method infers fat distribution from circumference ratios. It is free, repeatable at home, and correlates reasonably with lab methods when you measure at the same spots each time.

Men: 86.01·log₁₀(waist−neck) − 70.041·log₁₀(height) + 36.76
Method error
±3% vs DEXA
Male fitness band
14–17%
Female fitness band
21–24%
Use this elsewhere

Embed or cite it

Backlink-friendly embed

Embed this calculator

Free to embed on any site. Inputs preserved, link back to RevenueLab. Each format trades polish for SEO juice.

<script async src="https://www.revenuelab.fyi/embed.js"
  data-calculator="body-fat-percentage-calculator"
  data-title="Body Fat Percentage Calculator"
  data-query="sex=1&heightIn=70&waistIn=34&neckIn=15&hipIn=0&weightLb=180"></script>

Recommended — auto-resizes to fit, no scrollbars, and drops a crawlable link in your page.

Cite this calculator

Writing about this topic? Grab a citation — every link helps keep these tools free.

APA
RevenueLab. (2026). Body Fat Percentage Calculator. Retrieved from https://www.revenuelab.fyi/body-fat-percentage-calculator
HTML
<p>Source: <a href="https://www.revenuelab.fyi/body-fat-percentage-calculator" target="_blank" rel="noopener">Body Fat Percentage Calculator — RevenueLab</a> (2026).</p>
Markdown
Source: [Body Fat Percentage Calculator — RevenueLab](https://www.revenuelab.fyi/body-fat-percentage-calculator) (2026).

Measure the same way every time

Take measurements first thing in the morning, before eating, with the tape snug but not compressing skin. Waist is measured at the navel for men and at the narrowest point for women; neck is measured just below the larynx with the tape sloping slightly downward at the front.

  • Average three readings per site to reduce tape error.
  • Re-measure every 2–4 weeks, not daily.
  • Hip measurement is only used in the female equation.

FAQ

How accurate is the Navy body fat method?

It typically lands within about 3 percentage points of a DEXA scan, which is good enough for tracking change over time but not for precise single-point assessment.

What is a healthy body fat percentage?

Common fitness ranges are 14–17% for men and 21–24% for women. Essential fat, the minimum required for health, is roughly 3–5% for men and 10–13% for women.

Why did my body fat go up when my weight went down?

Usually a measurement or hydration artifact, or muscle loss during an aggressive deficit. Check whether lean mass also fell.

How this calculator is built

Independently maintained

Written by Sam Doshi and the RevenueLab editorial team. We don't sell the data feeds this tool is built on.

Sourced from primary data

Benchmarks come from public AdSense / Stripe / IRS disclosures and reader-submitted data — never third-party "$X per view" claims. Full methodology.

Last editorial review

Reviewed on a rolling quarterly cycle. Dated reviews are published on the methodology record for each calculator.

Editorial standards

See our editorial policy and disclaimer. Results are estimates, not advice.

Helpful?