Health Calculators

Health numbers are the kind you actually act on — what you eat today, how much water to drink, whether a symptom is worth a call to your doctor. The health calculators on this page turn a handful of basic body measurements into plain, personal numbers you can use right away. None of them diagnose a condition or replace a clinician; they give you a starting point and a way to track changes over time. **Calories and metabolism.** The calorie calculator and the BMR (basal metabolic rate) calculator both use the Mifflin-St Jeor equation, the method most often recommended for everyday estimates. Your BMR is the number of calories your body burns at complete rest — keeping you alive, nothing more. Layer your activity on top and you get your TDEE (total daily energy expenditure), the figure that tells you how many calories to eat to hold your weight steady, or to lose or gain gradually. Use the two together: set a target with the calorie calculator, then check the BMR calculator to see the floor below which you should not drop. **Water.** The water intake calculator estimates daily fluid needs from your body weight and how much you move, with an adjustment for hot weather. It is a guide, not a rule — thirst, kidney health, and medication all shift the real number. **Pregnancy.** The due date calculator works from your last menstrual period using Naegele's rule (40 weeks), adjusted for cycle length, and also estimates conception and the ends of each trimester. These dates are estimates; only an early ultrasound gives a precise gestational age. **Body fat.** The body fat calculator uses the U.S. Navy circumference method, which estimates body fat percentage from a few tape measurements. It is less precise than a DEXA scan or hydrostatic weighing, but it is free, private, and repeatable at home — useful for spotting trends, not for a single definitive reading. Every tool here runs entirely in your browser, keeps your inputs on your device, and needs no account. Metric units (cm, kg) are used throughout; convert first if you normally think in imperial. Re-measure under the same conditions each time — same scale, same time of day — so the numbers you compare are actually comparable. Use the results as a baseline, then bring questions to a qualified health professional.