Health calculators

What these tools do

Seven calculators covering common health and body composition questions. Each one states which formula it uses and each one is honest about where that formula fails, because every measure here has groups it describes badly.

Start with the right tool

Body composition. BMI compares weight to height and is the quickest screen, though it cannot distinguish muscle from fat. Body fat percentage separates the two using tape measurements. Ideal weight shows four different formulas so you can see how much they disagree.

Daily needs. The calorie calculator gives your resting metabolic rate, your maintenance level and a target for your goal. Water intake scales a daily fluid target to your weight, activity and climate.

Sleep and pregnancy. The sleep calculator works backward from your alarm in ninety minute cycles. The due date calculator estimates a delivery date and shows the milestones along the way.

Any units you like

Every measurement box has its own unit dropdown: height in centimeters, feet and inches, meters or inches; weight in kilograms, pounds or stone; tape measurements in centimeters, inches or millimeters. Switching converts what you have already typed rather than clearing it, and the calculation runs in metric internally, so every combination gives the same answer.