Are my health numbers uploaded to a server?

No. HealthTools is 100% client-side. Every calculation — BMI, BMR, body fat, ovulation — runs in your browser as plain JavaScript. There is no backend and no /api route. The Content-Security-Policy (connect-src 'self') even restricts which hosts the page may contact, so the privacy guarantee is enforced by the browser itself.

Are these calculations accurate?

Each calculator uses a standard, published method for its problem — the WHO BMI bands, the Mifflin-St Jeor equation, the US Navy body-fat method, Naegele's rule for the due date, and so on. A verify suite hand-checks reference values against the implemented math before every build. Still, these are educational estimates, not medical advice; consult a qualified professional for any health decision.

Why does the BMI calculator show two classifications?

People of Asian descent face metabolic risk at a lower BMI, so the WHO recommends Asian-Pacific cutoffs (≥23 overweight, ≥25 obese) alongside the standard Western bands (≥25 overweight, ≥30 obese). We show both so you can compare, which is especially relevant for a Hong Kong audience.

Where do the Cantonese food calories come from?

The food calorie database is a curated, build-time static snapshot bundled same-origin in the repo — it never makes a runtime request to any server. Values are approximate, drawn from public nutrition references, and you can refine them over time. Use them as a guide to portion sizes, not an exact count.

Does it work offline?

Yes. After the first load the app shell is cached, so every calculator works with no internet connection. Install HealthTools as a PWA and it opens and runs offline.

Body Composition

Body Fat Calculator

Body-fat percentage by the US Navy circumference method (waist, neck, hip, height).

Body Fat Calculator (US Navy)

Body-fat percentage from circumference measurements (waist, neck, hip, height).

SexHeight

Waist

Neck

Hip (women)

Weight (optional)

Your health numbers never leave your device — all math runs in your browser.

Result

Body fat

16.9%

Fitness

Fat mass12.7 kg

Lean body mass62.3 kg

The US Navy method estimates body composition from circumference. It is convenient but less precise than clinical methods (DEXA, hydrostatic).

US Navy circumference equations. Enter waist at the navel, neck below the larynx, hip at the widest point. Estimates vary ±3–4% vs clinical measurement. Educational estimate only — not medical advice. See a qualified professional for decisions about your health.

Printable PDF report, saved profiles & meal-plan compare are Pro features.

One-time unlock, no subscription. Unlock HealthTools Pro →

How to use this calculator

Choose your sex and enter your height.
Measure your waist (at the navel) and neck (below the larynx) in cm.
Women also enter the hip measurement; optionally add weight for lean body mass.
Read your estimated body-fat percentage.

Bookmark Body Fat Calculator — it works offline once loaded. Educational estimate only — not medical advice. See a qualified professional for decisions about your health.