How big is the difference between your biological and calendar age?
The typical spread between your biological and calendar age is around one to two years. Studies name no firm upper limit, but biological age does predict health risks better than your birth year.
Your calendar age is how many years you have lived. Your biological age reflects how old your body looks on the inside. The two do not have to match.
A study of more than 12,000 participants showed that the spread around the average difference was roughly 1.2 to 1.6 years. Individual outliers can be larger, but no study names a firm upper limit.
There is also no such thing as a single biological age. Your liver, kidneys and immune system can each age at their own pace. A measurement based on blood values can therefore give a different number than one based on your kidneys.
Biological age predicts health risks better than your birth year. In a study of 9,389 participants followed over 18 years, biological age predicted death considerably better than calendar age.
Epigenetic clocks, which look at the on-and-off patterns in your DNA, can differ quite a bit from one another. Good comparisons between these methods are still lacking. Two biological age tests can therefore give a different number, even on the same day.
All claims come from studies tracking groups of people over time or looking at associations; no controlled trials exist. Most studies measure biological age through blood values or DNA patterns, not through direct physical outcomes. The China Kadoorie Biobank and NHANES are the largest populations with concrete figures.
How can I measure my biological age?
DNA clocks, and GrimAge in particular, give the most reliable picture of your biological age. These measurement methods are currently used mainly in research.
Does your biological age change differently at night than during the day?
The night is biologically not a pause but an active recovery phase, and that phase deteriorates noticeably with age. Those who protect their sleep rhythm, with fixed times, limited screen use before bedtime and a longer nightly eating break, preserve that recovery function for longer.
Which lifestyle factors influence your biological age the most?
Sitting for prolonged periods, a disrupted circadian rhythm and muscle loss are the best-supported negative factors for your biological age; exercising regularly and maintaining a consistent sleep-wake rhythm are the most concrete steps you can take right now.
How often does it make sense to remeasure your biological age?
Clocks change slowly: two years is a realistic minimum to see the effect of a lifestyle change, but whether a lower score truly means you will live longer has not been proven. Track your daily weight, activity and blood pressure more frequently, and treat a remeasurement as a two-year check-in, not a weekly dashboard.
What does smoking do to your biological age?
Smoking measurably accelerates the biological ageing of lung cells, the immune system, and the reproductive system. Stopping smoking reverses some of that damage, in some cases even completely after ten years.
Can you see your biological age in your blood pressure?
A rising systolic blood pressure and a widening gap between the upper and lower numbers are recognisable signs of vascular ageing, but a truly reliable picture of your biological vascular age requires additional measurements that a general practitioner does not routinely perform.