Free Online Health & fitness
Health calculators ask for the most personal numbers on this site — your weight, your measurements, your age — which is exactly why they run entirely in your browser. The formulas are the published clinical ones, named on every page, and nothing you enter is uploaded, stored or profiled. Check the Network tab, or turn off your Wi-Fi and keep calculating.
- 01BMI CalculatorYour BMI and WHO category, metric or imperial.
- 02Calorie CalculatorDaily calories to maintain, lose or gain (TDEE).
- 03Body Fat CalculatorBody-fat % from a tape measure (US Navy method).
- 04Ideal Weight CalculatorHealthy weight range by four published formulas.
- 05Macro CalculatorProtein, carbs and fat grams for your calories.
- 06Water Intake CalculatorHow much water to drink a day, by body weight.
- 07BMR CalculatorCalories burned at rest, by three formulas.
- 08Due Date CalculatorYour due date and week of pregnancy, from your LMP.
- 09Ovulation CalculatorFertile window, ovulation day and next period.
- 10Sleep CalculatorBest times to sleep or wake, in 90-minute cycles.
- 11Pace CalculatorRunning pace per km and mile, plus race projections.
- 12Heart Rate Zone CalculatorFive training zones from your age and resting HR.
The BMI Calculator applies the WHO formula and bands, and shows the weight range that would put you in the normal band for your height. The Body Fat Calculator estimates body-fat percentage from tape measurements using the US Navy circumference method — the same equations the military uses for fitness assessments — and the Ideal Weight Calculator lays the four published formulas (Devine, Robinson, Miller, Hamwi) side by side rather than pretending there is one true number.
The Calorie Calculator estimates your BMR and daily energy expenditure with the Mifflin–St Jeor equation — the one the Academy of Nutrition and Dietetics recommends — and turns it into concrete daily targets for maintaining, losing or gaining. The Macro Calculator then splits any calorie budget into grams of protein, carbohydrate and fat, and the Water Intake Calculator estimates daily hydration from your body weight and training time.
Every one of these is a screening estimate, not a diagnosis. BMI cannot tell muscle from fat; tape-measure body fat is a trend tool, not a lab scan; calorie formulas describe the average person of your size, and real metabolisms scatter around that average. The pages say so plainly, because a health number without its limits attached is a worse answer, not a better one. None of it is medical advice — decisions belong with you and a clinician.
The privacy point matters more here than anywhere else on the site: these are numbers people rightly consider sensitive. The pages are static files; the arithmetic is JavaScript running on your device; there is no server-side code to receive your weight even if we wanted it. Load a calculator, disconnect, and it keeps working — which is the checkable proof.