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.

Energy & Calories

BMR Calculator (Mifflin-St Jeor)

Basal Metabolic Rate — calories your body burns at complete rest, via the Mifflin-St Jeor equation.

BMR Calculator (Mifflin-St Jeor)

Calories your body burns at complete rest — your Basal Metabolic Rate.

Weight

Height

Age

yrs

Sex

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

Result

Basal Metabolic Rate

1,649 kcal

per day, at rest

This is roughly the energy your body uses just to stay alive — breathing, keeping warm, and organ function — before any movement or activity.

Mifflin-St Jeor equation: Men 10·kg + 6.25·cm − 5·age + 5; Women … − 161. BMR is an estimate of resting energy and ignores body composition. 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

Enter your weight, height, and age.
Choose male or female (the equation differs).
Read your Basal Metabolic Rate — your resting calorie burn.

Bookmark BMR Calculator (Mifflin-St Jeor) — it works offline once loaded. Educational estimate only — not medical advice. See a qualified professional for decisions about your health.