Frequently asked questions about biological age

What biological age means, how it is calculated, how you can check yours, and where the limits of any estimate lie.

What is biological age?

Chronological age counts the years since you were born. Biological age is an estimate of how old your body appears to be, based on signals associated with health and ageing. Two people born on the same day can differ, because lifestyle and environment shape how the body ages.

What is the difference between biological age and chronological age?

Chronological age is a fact. It is fixed, it is identical for everyone born on the same day, and nothing changes it. Biological age is an estimate. It varies between people of the same chronological age and it can move in either direction. That difference is the whole point of the comparison: your chronological age tells you how long you have been here, while a biological age estimate is a prompt to think about how you have been living.

How is biological age calculated?

You always provide your chronological age. You may then add a selfie, a short lifestyle questionnaire covering sleep, exercise, smoking, alcohol, stress and body measurements, or both. Each answer is compared with what is typical for an adult, and the differences are weighted according to published research and applied to the age you entered. The engine is deterministic, so identical inputs always produce an identical result, and no language model decides your number.

Is my photo stored?

No. A photograph is processed only to produce your estimate and is discarded immediately afterwards. Your result is not stored either, so there is no account and no history to look back at. The only thing we ever keep is an email address, and only if you ask for early access and confirm it. The Privacy Policy explains this in full.

How can I find out my biological age?

There are three broad approaches. Laboratory epigenetic clocks read chemical marks on your DNA from a blood or saliva sample, which is the most researched method, although the tests are expensive and results differ between providers. Blood biomarker panels combine routine clinical measurements into a single figure. Questionnaire and appearance-based tools, including this one, use information you already have, which makes them free and instant but broader in what they can tell you. This calculator sits in the third group and is honest about what that means.

Is this biological age test free?

Yes, completely. There is no payment, no trial, no account, and no email address to hand over before you see your result. The calculator is free because the cost of running it is small and the purpose of the project is to be the most useful tool of its kind rather than the most profitable.

Do I need to upload a photo?

No. The Lifestyle Estimate needs nothing but your age and a short questionnaire, and it produces a full result with the same explanation as any other mode. A photo adds a second, independent signal, so the Complete Estimate draws on more information than either mode alone, but it is always optional.

How accurate is the estimate?

Treat it as a wellness estimate rather than a measurement. No clinical test exists that this calculator reproduces, and no validated model takes a selfie and a lifestyle questionnaire as its input. Every result is shown with a range and a label describing how much information you provided, because we would rather be honest than imply precision that does not exist.

What is a good biological age?

A biological age at or below your chronological age is the more encouraging result, and a wider gap below suggests your answers sit better than typical across the areas the calculator asks about. There is no target to hit and no score to beat. A result close to your chronological age is the most common outcome and is not a problem, because the estimate is built around what is typical rather than around an ideal.

Why is my biological age higher than my chronological age?

Because one or more of your answers sat further from typical in an unfavourable direction, and the result screen names which ones. Short sleep, little physical activity, smoking, heavy drinking and sustained stress are the usual contributors. The estimate reflects the information you gave rather than a diagnosis, so treat a higher result as a prompt to look at those habits rather than as evidence that something is wrong.

Can I improve my biological age?

The habits the questionnaire asks about are consistently associated with long-term health, so changing them may change your estimate. That is a change in the information you provided rather than proof that your body has changed. Use the result as encouragement, not as evidence.

How often should I check my biological age?

There is little value in checking daily, because the questionnaire asks about habits that move over months rather than hours. Every few months is enough to notice a genuine change in how you sleep, move or handle stress. Since nothing is stored, you would need to keep a note of a previous result yourself in order to compare.

Is this medical advice?

No. This is an educational wellness tool, not a medical device. It cannot diagnose, treat or rule out any condition. Please speak to a qualified healthcare professional about any health concern, and never use this estimate to make a medical decision.

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Still comparing the two ideas? The homepage has a side-by-side of biological and chronological age.