BMI is a screening tool, not a diagnostic one. It correlates well with body fat at a population level but misclassifies some individuals — particularly athletes (high muscle reads as overweight) and older adults. Use it alongside body fat percentage and waist circumference for a fuller picture.

TDEE (Total Daily Energy Expenditure) is the total calories you burn in a day, factoring in your activity level. To lose weight sustainably, eat roughly 300-500 kcal below your TDEE — that creates about 0.3-0.5 kg of fat loss per week.

The standard Naegele's Rule adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). Our Due Date Calculator also shows your trimester dates and key milestones.

It shows four results — Devine, Robinson, Miller, and Hamwi — so you can see the range rather than a single number. Most clinical settings use Devine for drug dosing.

Most calculators here are validated for adults (18+). BMI for children uses different age- and sex-specific percentile charts — the standard adult BMI scale does not apply. For paediatric BMI, consult your paediatrician.