Biological Age Calculator
Without a Blood Test
This calculator gives an educational estimate based on lifestyle factors. It is not a medical test, a diagnosis, or medical advice, and it does not replace seeing a doctor. Talk to your GP about your health.
An estimate built from habits, not biology
Your chronological age counts birthdays. Everyone born on the same day has the same number.
Biological age asks a different question: how is this particular body tracking? There are two ways to approach it. You can measure the body directly, through blood markers or DNA methylation. Or you can estimate from the things known to influence how a body ages, which is what this calculator does.
The second approach is less precise. It has to be. It is working from how you live rather than from what is happening in your cells. What it offers instead is accessibility: no blood test, no cost, no waiting, and an answer in two minutes.
Treat the number as a prompt rather than a measurement. If it comes back higher than your actual age, the useful response is not alarm. It is a conversation with your GP about what is worth measuring properly.
Five factors, one published study
The five factors, and why they are in the model
The model is deliberately simple: five lifestyle factors, scored against the definitions used in the original research. Sleep is asked about but not scored because it was not one of the five factors in that study.
Have recent bloods? There’s a more direct version
This calculator infers from habits. If you have had a blood test in the past year, you can estimate your biological age from what is actually in your blood instead, using nine markers and the published PhenoAge method.
It is the more precise of the two. Both are free.
If you want to move the number
Two caveats first. Most of this evidence is associational: it shows that people who do these things tend to have better outcomes, not that doing them will change your result by a set amount.
And a score changing is not the same as ageing slowing down. Treat the below as reasonable, well-supported directions rather than a protocol.
Smoking
The largest single factor here, and the only one where the direction is completely uncontested.
Cardiorespiratory fitness
A meta-analysis of 37 studies covering 2,258,029 participants found roughly half the mortality risk in the fittest third compared with the least fit third. Of everything on this list, this has the strongest evidence behind it.
Body composition
Worth noting that the underlying goal is metabolic health rather than a number on a scale. BMI is the model’s proxy for it, not the thing itself.
Diet quality
The pattern matters more than any single food. The index used in the original study rewarded vegetables, fruit, wholegrains, nuts and legumes, and penalised processed meat and sugary drinks.
Sleep
Not scored here, but consistently short or poor-quality sleep is associated with higher inflammatory markers and worse metabolic measures.
What to do with this
If your estimate came back higher than your actual age, the useful next step is not a supplement or a protocol. It is finding out what is actually happening in your body, which means measurement and a clinician.
TAKE CONTROL OF YOUR HEALTH
Habits are half the picture. Measuring is the other half.
The honest limits of a lifestyle estimate
It is self-reported. Everything here comes from what you tell it. People systematically underestimate alcohol and overestimate exercise, and no calculator can correct for that.
We weighted the five factors equally. The study does not claim they contribute equally, and they almost certainly do not. We split the range evenly because it makes the arithmetic simple enough to show you in full, and we judged a transparent approximation more useful than a hidden one. That is a trade-off, and you should know we made it.
One year of life expectancy is not one year of age. Converting between them is a simplification. The underlying research reports life expectancy; the age framing is our translation of it.
The research population was not diverse. The cohorts were US health professionals, predominantly white, in the Nurses’ Health Study and the Health Professionals Follow-up Study. How well the findings transport to the broader Australian population is an open question.
Five factors is five factors. It knows nothing about your genetics, your family history, your medical conditions, your medications, your bloodwork, or your environment. Plenty that matters is simply not in the model.
A good score is not a clean bill of health. People with excellent habits still develop serious illness. That is precisely why screening exists and why habits alone cannot substitute for measurement.
Sources
The model
Circulation
Impact of Healthy Lifestyle Factors on Life Expectancies in the US Population
https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.117.032047Circulation
Correction: Impact of Healthy Lifestyle Factors on Life Expectancies in the US Population
https://www.ahajournals.org/doi/10.1161/CIR.0000000000000587Health Promotion Journal of Australia
Biological age calculators to motivate lifestyle change: Environmental scan of online tools and evaluation of behaviour change techniques
https://onlinelibrary.wiley.com/doi/abs/10.1002/hpja.671
Supporting evidence
Mayo Clinic Proceedings
Objectively assessed cardiorespiratory fitness and all-cause mortality risk: a systematic review and meta-analysis
https://www.mayoclinicproceedings.org/article/S0025-6196(22)00133-1/abstract
FAQs
