Age Calculator
Calculate your exact age in years, months, days, hours, and minutes. Find out how many days you've lived and how many days until your next birthday.
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Defaults to today. Change to calculate age on any date.
Select your date of birth
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The age calculator computes your exact chronological age from your date of birth to any target date — defaulting to today. It accounts for leap years, months of varying length (28–31 days), and provides your age broken down into years, months, and days, as well as total days, hours lived, days until your next birthday, and your Western zodiac sign.
How Age Is Calculated
Age calculation is more complex than it appears because months have different lengths (28–31 days) and leap years add a day to February every four years. The algorithm used by this calculator:
- Start with the birth date and target date.
- Count complete calendar years between the two dates.
- Count complete months since the last birthday year.
- Count remaining days since the last complete month boundary.
- Compute total days by summing each individual day elapsed, accounting for all leap years.
What Is Biological Age?
Chronological age — what this calculator measures — is simply how much time has elapsed since your birth. But your body may age faster or slower than the calendar. Biological age is determined by markers like:
- Telomere length: Telomeres shorten with each cell division. Chronic stress, poor diet, and lack of exercise accelerate shortening.
- Epigenetic clock: DNA methylation patterns change predictably with age and can be used to estimate biological age within a few years.
- VO₂ max: Cardiorespiratory fitness is one of the strongest predictors of longevity. High VO₂ max is associated with a younger biological age.
- Grip strength: A surprisingly reliable predictor of biological age and future health outcomes.
How Exercise Slows Biological Aging
Regular physical activity is the single most evidence-backed intervention for slowing biological aging. Studies show that people who exercise regularly have telomeres that are biologically 9 years younger than sedentary peers of the same chronological age. The mechanisms include reduced inflammation, improved mitochondrial function, maintained muscle mass, and improved cardiovascular health.
Frequently Asked Questions
Exact age is calculated by finding the difference between the date of birth and the current date (or a target date). The years component is the number of complete calendar years elapsed. The months component counts full months after the last birthday year. The days component counts remaining days after the last complete month. This calculator also computes total days lived, hours, and minutes for a complete picture.
Leap years (every 4 years, except century years not divisible by 400) add a day to February. People born on February 29 legally celebrate their birthday on March 1 in non-leap years in most jurisdictions. This calculator correctly accounts for all leap years when computing total days lived and the exact date breakdown.
Chronological age is your age in calendar time since birth — what this calculator computes. Biological age reflects how old your body actually is based on physiological markers like telomere length, epigenetic clock, cardiovascular health, and metabolic function. Biological age can be 10–20 years younger or older than chronological age depending on lifestyle factors such as exercise, diet, sleep, and stress management.
Your age "at last birthday" is the whole number of years since you were born — the number most people mean when they say their age. Your exact age includes the fraction: months and days since your last birthday. For example, if you are 35 years, 8 months, and 12 days old, your age at last birthday is 35. This calculator shows both.
Yes — this calculator defaults to today but lets you change the "as of" date to any date in the past or future. This is useful for legal purposes (age at time of event), historical research, or calculating how old someone will be on a future date such as a birthday, anniversary, or legal milestone.
The number of days you have lived is your exact age in days. For a 30-year-old, this is approximately 10,957 days (30 × 365 + leap year days). For a 40-year-old, approximately 14,610 days. This calculator computes the exact number accounting for all leap years, months of varying length, and partial months.