Medical disclaimer

Everything on this site (every calculator, result, chart and article) is informational and educational. It is not medical advice, not a diagnosis, and not a substitute for consultation with a qualified health professional who can examine you and knows your history.

The formulas here are population-level screening tools with known error bands, which we state alongside results. They cannot account for your medications, medical conditions, pregnancy, athletic background or anything else that makes you a person rather than a statistic.

Please talk to a doctor, registered dietitian or other qualified clinician before acting on any number from this site, especially before starting a calorie deficit, and always if you are under 18, pregnant or breastfeeding, have a history of disordered eating, or manage any medical condition.

Two of our tools sit closest to clinical practice, and both need a clinician rather than a calculator. If you are looking up a child's BMI-for-age, the percentile tells you only where one measurement sits on a reference population on one day (it cannot see growth over time, puberty, build or family pattern), so take any result that concerns you to your GP, paediatrician or child health nurse rather than changing how a child eats. If you are pregnant, the weight-gain ranges are guidance written for a conversation with the midwife or obstetrician who is tracking your pregnancy and can weigh things this page cannot; they are never a target to chase, and never a reason to restrict your eating on your own.

If eating or weight concerns are weighing on you, free confidential support exists: Butterfly Foundation 1800 33 4673 (Australia), Beat 0808 801 0677 (UK), or the NEDA resources at nationaleatingdisorders.org (US).

How every number here is calculated is set out on the methodology page, and the sources behind them are listed on the references page.