Health & Fitness

Health numbers are among the most personal data anyone types into a website, which is exactly why these six tools were built to calculate locally and store nothing. The Fitness Dashboard brings together body mass index, body fat estimation, daily calorie needs based on activity level, and macronutrient targets, so you can see the whole picture from one set of inputs instead of visiting four separate calculators. The Hydration Timer works out a sensible daily water target from your weight and activity and then paces reminders across your waking hours. The Runner's Pace Predictor converts a finishing time into a per-kilometre pace and estimates equivalent times at other distances. The Sleep Cycle Planner works backwards from when you must wake, suggesting bedtimes that fall between ninety-minute cycles rather than in the middle of one. The Period & Ovulation Calculator and Pregnancy Due Date Calculator handle cycle and gestational dating.

These are estimates built on population averages, and their value comes from tracking change over time rather than from any single number. Body mass index, for example, uses only height and weight, so it consistently overstates risk for muscular people and understates it for those with low muscle mass, which is why the Fitness Dashboard shows it alongside other measures rather than alone. Calorie targets assume an average metabolism and an honestly reported activity level; if your weight is not moving in the direction the numbers predict after a few weeks, adjust the target rather than doubting the scale. Cycle predictions assume reasonably regular cycles and become unreliable when cycles vary widely, and a due date derived from a last menstrual period is routinely revised by an early ultrasound, which is more accurate. Use these figures to prepare questions for a doctor, not to replace one.

Weight, cycle dates, pregnancy status and fitness history are sensitive in ways that ordinary personal data is not, and in several countries they have been used commercially and legally in ways people did not anticipate when they typed them into an app. Every calculation on this page happens inside your browser. Nothing is submitted to a server, no account exists to be breached, no profile is built, and no advertising identifier is attached to what you enter. If a tool offers to remember your figures between visits it does so using your browser's own local storage on your device, and clearing your browser data removes it permanently. This is also why the tools continue to work with your connection turned off.