Biological age calculator
Estimate how sleep, steps, training, smoking and body measurements compare with your chronological age.
Calculate biological ageLongevity Plussing: small habits, measurable progress
Longevity Plussing is fjt’s name for making small, repeatable improvements to the habits that support healthspan. It is not a clinical method or a promise to add years to life: it is a practical way to notice trends, choose one next step and keep going.
The fjt approach to healthy ageing
Start with two useful estimates
Use the free calculators without an account. Your entries stay in your browser and the results are educational estimates, not medical diagnoses.
VO₂max calculator
Estimate cardiorespiratory fitness with the NTNU/HUNT non-exercise model—no running test required.
Calculate VO₂maxWhat biological age can—and cannot—tell you
Chronological age is time since birth. Biological age is an umbrella term for estimates of how the body is functioning. Different methods use different inputs, so two tests can produce different numbers.
fjt’s calculator uses lifestyle and functional signals. It does not measure DNA methylation, blood biomarkers or disease risk. The most useful reading is the direction of a consistently measured trend, not one isolated result.
Why VO₂max belongs in the picture
VO₂max describes the greatest amount of oxygen the body can use during intense exercise and is a standard marker of cardiorespiratory fitness. Laboratory gas analysis is the direct measurement; equations, field tests and wearables provide estimates.
The fjt calculator uses a published non-exercise model based on age, sex, body mass index, resting heart rate and activity. It is useful for orientation and repeatable tracking, but it can differ from a laboratory result.
What Longevity Plussing looks like in practice
Begin with a baseline, then choose a change small enough to repeat: a steadier wake time, a short walk after meals, regular aerobic work, two weekly strength sessions or support to stop smoking.
Repeat the same measurement method and review several weeks together. Sustainable patterns matter more than a perfect day, and symptoms or health concerns belong with a qualified clinician—not an online score.
A simple Longevity Plussing loop
- 1EstimateUse biological age and VO₂max as starting points, with their limitations in view.
- 2Choose one plusPick one realistic change in movement, sleep, recovery or tobacco use.
- 3Repeat consistentlyUse the same inputs and method so the trend remains comparable.
- 4Review the trendLook across weeks and adjust gradually instead of reacting to one day.
Important limits
The calculators provide statistical estimates for education and self-observation. They do not diagnose, prevent or treat disease, and they cannot predict how long you will live. Seek medical advice for symptoms, risk assessment or decisions about treatment and exercise safety.
Frequently asked questions
How do I calculate my biological age?
Enter sleep, steps, training, smoking status and body measurements in the fjt biological age calculator. It returns an educational estimate compared with your chronological age—no blood test or account needed.
What is the difference between biological age and chronological age?
Chronological age counts years since birth. Biological age estimates how your body is functioning; depending on the method it may be higher or lower than your calendar age.
How can I increase my VO₂max?
Regular aerobic training, a mix of steady sessions and short intervals, and gradual progress over weeks are the most common approaches. Check with a clinician before intense training if you have health concerns.
What is a good VO₂max for my age?
VO₂max naturally declines with age and differs by sex. The fjt VO₂max calculator shows how your estimate compares with people of the same age and sex.