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.

Hydration

Water Intake Calculator

Daily water requirement from your body weight, with an activity-level adjustment.

Water Intake Calculator

Daily water requirement from your body weight, with an activity adjustment.

Weight

Activity level

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

Result

Daily water

2.95 L

12 glasses (250 ml)

250-ml glasses12

Based on ~35 ml per kg of body weight, plus extra for activity. Needs rise in heat, illness, or pregnancy; much of your water also comes from food.

35 ml/kg + activity adjustment (0 / 500 / 750 / 1000 ml). Thirst and urine colour are better individual signals than any formula. 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 in kilograms.
Choose your usual activity level.
Read your estimated daily water intake in litres and glasses.

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