Methodology
How the BioAge test works
The BioAge test estimates how old your body is biologically. Here you can find out which answers go into the estimate, how they become a number and where the limits are.
What the test covers
The test asks about habits and circumstances that studies link to the pace of ageing. It deliberately focuses on factors you can influence. Genetics and sex are not included: they cannot be changed, and the test is meant to show where you yourself can make a difference.
The 25 questions are spread across five areas. Not every area counts equally. The weighting comes from the lifestyle models by Bamberger and Despeghel and was adjusted on the basis of current studies:
- Life satisfaction (8 questions): 35.7 %. This covers stress, happiness, social relationships, satisfaction with your main activity, hobbies and relaxation.
- Nutrition (5 questions): 18.1 %. Fruit and vegetables, fish, meat, fluid intake and body mass index.
- Exercise (4 questions): 18.0 %. Endurance, strength training, everyday movement, and balance and flexibility.
- Consumption (3 questions): 15.6 %. Smoking and alcohol.
- Self-care (5 questions): 12.6 %. Sleep, sun protection, check-ups and oral health.
Questions within an area also carry different weights. A reliable social network, for example, counts for more than satisfaction with your job, because its link to life expectancy is far better established.
How your answers become a number
1. The possible range. The starting point is your calendar age. According to Bamberger's model, lifestyle can shift biological age by around 46 % of calendar age, roughly 23 % down and 23 % up. At 40, this range runs from about 31 to 49 years.
2. Points per answer. Each answer is given a value between 0 and 1. 0 stands for the most favourable habit, 1 for the least favourable. For the sliders, what counts is where you set the slider. For body mass index, what counts is the range your value falls into; if you enter your waist circumference, it is included too.
3. Result per area. The weighted points of an area determine where you stand within the range: far left if all answers are favourable, far right if all are unfavourable. This produces the five bars on your result page.
4. A special case: consumption. Not smoking and drinking little alcohol does not make you younger than your calendar age in the test. It protects you from ageing faster. That is why the consumption bar starts at your calendar age and can only go up.
5. Your overall result. The five area values are combined into one number according to their weighting. At 40, the result ranges from about 32.2 to 50.7 years depending on lifestyle. The timeline on your result page shows this range for your age.
How your biggest levers are chosen
For each question, the test calculates how much it currently contributes to your result: the weight of the question times your points. The three questions with the largest contribution appear as your biggest levers, provided there is real room for improvement.
“Up to … years younger” shows how much younger your result would be if you could give the most favourable answer to this one question and everything else stayed the same. “What you're already doing really well” lists habits for which you already gave the most favourable or a very good answer.
Where the limits are
It is an estimate, not a measurement. Biological age can be determined in a lab, for example with epigenetic clocks. The BioAge test measures none of this. It uses your answers to estimate which way your lifestyle is pushing.
It relies on your own answers. Self-assessments are sometimes off, for example on sleep or exercise. The result is only as accurate as the answers.
Research mainly shows associations. Many findings come from observational studies. They show robust associations, but no final proof of cause and effect. The test's weighting is a model that summarises this evidence in simplified form.
It is not a substitute for a medical examination. The test does not make a diagnosis and says nothing about individual diseases. It is a motivational tool: it is meant to show where a change could be particularly worthwhile for you.
What happens to your answers
The calculation runs entirely in your browser. Your answers are not sent to a server, not stored and not analysed. If you reload the page, they are gone. The share image is also created in your browser and is only sent if you share it yourself.
Scientific basis: Weighting models based on Bamberger 2006 and Despeghel 2016 · Despeghel & Krüger, Die BioAge Challenge · Blackburn & Epel, The Telomere Effect 2017 · Holt-Lunstad, Smith & Layton, PLoS Medicine 2010 (öffnet in neuem Tab) · Belsky et al., PNAS 2015 (öffnet in neuem Tab) · Horvath, Genome Biology 2013 (öffnet in neuem Tab)
For more background, read Biological age explained and the individual articles in the knowledge section.