What has your
body been through?

Most of us know our numerical age. But biological age — the real condition of your organs, your brain, your cardiovascular system, your hormones — is something different. It is shaped not just by the years you have lived, but by how you have lived them: what you eat, how much you exercise, how much you sleep, whether you smoke, and how much stress you carry.

HowOldIsMyBody.org translates decades of peer-reviewed medical research into a personalised, interactive journey through your own body. Starting with your brain and ending at your legs and joints, the tool shows you — in real time — what population science says is happening inside you right now, based on your age, sex, and lifestyle choices.

Every figure shown is grounded in published research. We draw on data from NHS England, NICE clinical guidelines, the British Heart Foundation, the World Health Organization, and peer-reviewed studies published in journals including The Lancet, BMJ, and Nature. Where a clinical threshold exists — for blood pressure, cholesterol, lung function, bone density — we use it. Where population averages exist, we cite them. Nothing is estimated or invented.

The result is not a diagnosis. It is education — a way of understanding what the science says is probable for someone of your age and lifestyle profile, so you can make better-informed decisions. Individual variation is always significant, and we make this clear throughout.

Beyond the main calculator, the site contains in-depth guides for every major body system — covering neuroplasticity and cognitive decline, cardiovascular risk, hormonal changes including perimenopause, skin ageing by decade, lung function, liver health, gut microbiome changes, and musculoskeletal decline. Each section is referenced against clinical guidelines and is updated when new guidance is issued.

Use the body system navigation above to explore a specific area, or take the full calculator to receive your personalised head-to-toe assessment.