Health Tools

Health tools answer the everyday body-related questions people search for: what is my BMI, how many calories should I eat, when is my baby due, and how much of my weight is fat. Each tool is built around a formula with a well-defined clinical standard — BMI uses the WHO weight-for-height classification, the calorie calculator uses the Mifflin-St Jeor equation for basal metabolic rate, the due date calculator uses Naegele's rule with cycle-length and IVF-transfer adjustments, and the body fat calculator applies the US Navy circumference formula to a few tape measurements. All of them produce their results the moment you type, because a health number you have to wait for is a health number you will not use. Just as importantly, every calculation runs entirely in your browser: your weight, height, and medical dates are exactly the kind of sensitive information you should never have to upload to a stranger's server.

How to Use

Use the bmi-calculator when you want a quick, standardized read on whether your weight is in a healthy range for your height. It works in both metric and US units, shows exactly where you fall on the WHO scale, and tells you the healthy weight range for your height — the number most people actually want. Use the body-fat-calculator when BMI is not enough and you want to know what share of your weight is fat: it applies the US Navy tape method with nothing more than a flexible measuring tape, or falls back to a BMI-based estimate when you have no tape at hand, and shows your body fat percentage, category, fat mass, and lean mass. Use the calorie-calculator when you are planning a diet or an exercise program: it computes your basal metabolic rate (BMR) from the Mifflin-St Jeor equation, then applies your activity level to estimate total daily energy expenditure (TDEE), and finally shows calorie targets for losing, maintaining, or gaining weight. Use the due-date-calculator when you are pregnant or planning a pregnancy: enter the first day of your last period, your conception date, or an IVF transfer date, and it estimates the due date, current gestational age, and key trimester milestones.

Tips & Best Practices

The health tools look similar — enter a few numbers, get a result — but they answer fundamentally different questions. The bmi-calculator is a screening tool: it classifies your current weight-for-height into WHO categories and shows how far you are from the healthy range. It says nothing about how much you should eat. The body-fat-calculator refines what BMI cannot see: two people with the same BMI can carry very different amounts of fat, and the Navy tape method splits your weight into fat mass and lean mass to tell them apart. The calorie-calculator is a planning tool: it estimates how much energy your body burns per day and derives intake targets from that. It says nothing about where you currently stand. A practical workflow is to run them together: BMI tells you whether to aim for maintenance, loss, or gain; the body fat calculator tells you whether the weight you carry is fat or muscle; the calorie calculator tells you what to actually do about it. The due-date-calculator belongs to a different domain entirely — obstetrics rather than nutrition — and is built around date arithmetic (Naegele's rule) instead of body measurements. One caution that applies to all of them: they are estimates for guidance, not clinical instruments. BMI misclassifies very muscular people, tape-based body fat has a ±3-4% error margin, calorie equations have a ±10% error margin, and only about 4% of babies arrive exactly on their due date. Use them to orient yourself, and consult a professional for decisions.

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