Free · 12 questions · around 2 minutes
Biological age test: work out your lifestyle age
This free biological age calculator works from your habits, not lab tests. Answer 12 quick questions on sleep, light, activity, smoking, alcohol, food and social life. You will see which answers raise your lifestyle age, which lower it, and the study behind each figure.
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Your estimate
Your lifestyle age
This is an estimate of how your habits compare in large studies. Nothing about your body is measured.
Habits with the most room for change
None of your habits has much room for change: every answer is already at or close to the most favourable option.
How each answer counts
Change the answer in any row and watch your lifestyle age update.
- Lowers your lifestyle age
- Raises your lifestyle age
- No sign-up or email
- Calculated in your browser
- Every figure linked to its study
How it works
From habits to a lifestyle age
Every habit question draws on large studies that followed adults, often hundreds of thousands of them, for years. For each habit group, researchers set the risk of death over that period against a reference group. This comparison is called a hazard ratio.
Adult mortality climbs steeply with age: the yearly risk of death roughly doubles for each additional eight years. So a habit tied to twice the risk counts as 8 extra years, and one tied to half the risk as 8 fewer. The scientific name for this conversion is the rate advancement period.
Add the years from all your answers, positive or negative, to your actual age and you have your lifestyle age. Each habit is centred on a typical answer that counts as zero, so an average set of answers lands near your actual age.
Limits of this test
- It works from your answers alone: no blood test, DNA sample or scan is involved.
- The studies observed people rather than running experiments. They link habits to risk but cannot show that any single habit is the cause on its own.
- The years for each habit are simply added up. In reality habits overlap, for example activity and body weight, so the total is approximate.
- Your answers are matched to the groups each study used. Three are stand-ins: in the sleep-timing and light studies, people wore a sensor on the wrist for a week, while this test uses how much your bedtime moves, how long you spend outdoors and how dark your bedroom is instead.
- The figures are averages, mostly from middle-aged and older adults in Western countries such as the UK and the US, so results for people under about 30 or over about 80 are less certain. The total is limited to 12 years below and 20 years above your actual age.
The studies behind the numbers
Questions and answers
What is biological age, and how is this test different?
Biological age usually means an age estimated from lab markers, such as blood values or the DNA patterns read by epigenetic clocks. This test takes no samples. Instead, it takes the habits linked to mortality risk in large studies and converts them into years. That gives you a lifestyle age to set against your actual age, and shows which of your habits carry the most weight.
How accurate is this estimate?
See it as a rough guide. The figures are group averages from very large studies, so they cannot describe any one person exactly. Your genes, your health history and anything the 12 questions leave out also play a part. The result is most useful for comparing your habits with each other, less so as an exact number.
Which habits count most, and does changing them change the result?
In this model, smoking counts most: at least one cigarette a day adds almost 12 years. BMI follows with up to 8 years, then activity, where the gap between almost none and 300 minutes or more a week is about 5.5 years. The result is calculated from your answers, so if your habits change, the lifestyle age changes with them. You can try this in the breakdown that comes with your result. In the studies, people whose habits were more favourable had a lower risk of death than those whose habits were less so.
Why are daylight and a dark bedroom part of the test?
The body clock takes its timing from light. A UK Biobank study published in 2024 looked at over 88,000 adults who had worn a light sensor on the wrist for a week, and followed them for about eight years. People whose days were bright and whose nights were dark had a lower risk of death over that time than people with the opposite pattern. Street light or neon through the curtains counts as night light too.
Are my answers stored anywhere?
No. The test does its sums inside your browser and keeps nothing: no answers are saved or sent, and there is no sign-up. Close the page and they are gone.
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