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

Calorie Deficit Calculator

Target-date planner: a daily calorie deficit → the date you reach your goal weight (and the inverse).

Calorie Deficit Calculator

A daily calorie gap → the date you reach your goal weight (≈ 7,700 kcal per kg).

Current weight

Goal weight

Daily calorie gap

kcal

Start date

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

Result

Reach your goal by

19 Mar 2026

5 kg loss

Days to goal77

Weeks to goal11

Implied weekly rate0.45 kg / week

Total energy gap38,500 kcal

A 0.5–1% body-weight loss per week is generally considered a safe rate. Larger deficits are harder to sustain.

Uses ≈7,700 kcal per kg of body tissue. Real weight change varies with water, muscle, and adaptation. 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 current weight and your goal weight.
Enter the daily calorie gap (deficit for loss, surplus for gain).
Pick a start date.
Read the projected target date and weekly rate.

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