Healthzio provides free, accurate health and fitness calculators to help you make informed decisions about your body and wellbeing.
All calculations are based on established medical formulas — Mifflin-St Jeor for calories, US Navy Method for body fat, Devine/Robinson/Miller/Hamwi for ideal weight, and more.
No sign-up required. No data stored. Everything runs in your browser.
Most online health calculators bury a simple formula under sign-up walls, paid premium tiers, or aggressive newsletter prompts before they'll show you a single number. Healthzio is a deliberate alternative: pick a calculator, enter your numbers, get a result, leave. No emails, no accounts, no upsell. Calculations run entirely in your browser using JavaScript, so the height and weight you type never leave the device. We picked the formulas with the strongest peer-reviewed track record — Mifflin-St Jeor outperforms Harris-Benedict for modern populations; the US Navy body-fat method needs only a tape measure; Devine, Robinson, Miller and Hamwi are the four ideal-weight equations clinicians actually reference. Each tool shows the formula it uses so you can verify the math.
Anyone who needs a quick, neutral health-related number without medical-app overkill: someone starting a fitness journey checking their BMI for the first time; a runner working out half-marathon pace; an expectant parent wanting a due-date estimate; a lifter calculating one-rep max from a five-rep set; a dieter sizing macros for a fat-loss target. The calculators are educational, not clinical. None of them replace a doctor, dietitian, or qualified trainer — but they are the same tools those professionals reach for when they need a fast estimate.
Healthzio is one of about twenty independent single-purpose web utilities run by the same developer. Sister sites include Toolzio (everyday calculators), Wordzio (writing tools), Blitzzio (live chess), TypeBlitz (typing speed), and Sudokuzio (sudoku). Each does one job well rather than trying to be a portal.
Part of the Toolzio network of free tools.
⚠️ All content is for educational purposes only and is not a substitute for professional medical advice.