Free health & fitness calculators
BMI (with Asian-Pacific cutoffs), BMR & TDEE, macros, body fat, ideal weight, water intake, calorie deficit, ovulation & due date — plus a Hong Kong Cantonese food calorie lookup. All the math runs in your browser. No signup, no upload.
All calculators
Body Composition
BMI Calculator
Body Mass Index with WHO Asian-Pacific cutoffs (≥23/≥25) and standard Western bands (≥25/≥30).
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Body Fat Calculator
Body-fat percentage by the US Navy circumference method (waist, neck, hip, height).
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Ideal Weight Calculator
Healthy weight range from the Devine formula, with Robinson, Miller, and Hamwi for comparison.
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Energy & Calories
BMR Calculator (Mifflin-St Jeor)
Basal Metabolic Rate — calories your body burns at complete rest, via the Mifflin-St Jeor equation.
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TDEE Calculator
Total Daily Energy Expenditure — BMR multiplied by your activity level to estimate daily calories.
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Macro Calculator
Protein, carb, and fat targets in grams for a cut, maintenance, or bulk — from your calories and goal.
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Calorie Deficit Calculator
Target-date planner: a daily calorie deficit → the date you reach your goal weight (and the inverse).
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Frequently asked questions
- 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 — the WHO BMI bands, the Mifflin-St Jeor equation, the US Navy body-fat method, Naegele's rule. A verify suite hand-checks reference values against the implemented math before every build. 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 cardiometabolic 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 — especially relevant for a Hong Kong audience.
- Where do the Cantonese food calories come from?
- The food 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 refineable. 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.
Health numbers that never leave your device
HealthTools is a free, private health calculator hub. Your weight, measurements, and cycle dates stay in your browser — there is no server, no upload, and no tracking.