Age Calculator
Calculate exact age in years, months, and days between two dates.
How to use the Age Calculator
- Enter the date of birth.
- Leave "Calculate age on" set to today, or change it to any other date — useful for an age on a past event or a future deadline.
- Read the exact age in years, months, and days, plus the total number of weeks lived.
About the Age Calculator
An age calculator finds the exact time elapsed between a date of birth and another date — usually today — broken down into years, months, and days rather than just a single 'years old' number. This accounts correctly for varying month lengths and leap years, which manual subtraction often gets wrong.
Beyond checking your own age, this tool is useful for calculating a child's age for school enrollment cutoffs, figuring out how long until a milestone birthday, or measuring the exact duration between any two dates, such as an anniversary or a contract period.
Worked example
Example: someone born on March 12, 1990 checking their age on September 15, 2026 would see '36 years, 6 months, 3 days' — a precise breakdown rather than just '36'.
How years, months, and days are counted
The calculator first counts whole years, then whole months on top of them, then the days left over — the same way you'd count on a calendar. A month is complete when the end date reaches the same day-of-month as the birth date. When that day doesn't exist in a shorter month, the last day of the month is used instead: from January 31 to March 1 of a non-leap year is 1 month and 1 day, because the one-month mark falls on February 28.
The total-weeks figure is different: it counts the exact number of days between the two dates and divides by seven, ignoring months altogether. That's why it's handy for things measured in weeks, like a baby's age or a training plan.
Birthdays on February 29
People born on a leap day are a well-known edge case. In non-leap years this calculator treats February 28 as the anniversary, so a leap-day baby turns a year older on February 28. Legal rules differ by country — some treat March 1 as the official birthday in common years — so check the local rule when age matters for a document or eligibility cut-off.
Practical uses beyond 'how old am I'
- School and sports cut-offs: set 'Calculate age on' to the cut-off date to see the age that counts, not today's age.
- Retirement or benefits planning: enter a future date to check exactly when a threshold age is reached.
- Durations: the tool measures the time between any two dates, so it works just as well for tenancy, employment, or warranty periods.
- Historical dates: enter a past date to find someone's age at a particular event.
Frequently asked questions
- Does the calculator account for leap years?
- Yes. The calculation is based on actual calendar dates, so leap years (like February 29) are automatically factored into the day count without any extra input needed.
- Can I calculate age as of a future or past date, not just today?
- Yes — set the 'calculate age on' field to any date, past or future, and the tool will compute age as of that specific date instead of today.
- Why does my age in months look different from years × 12?
- Because months have different numbers of days, the months-and-days breakdown reflects actual elapsed calendar time, which can differ slightly from a simple multiplication of years by 12.
- Is this the same as my 'legal age' for enrollment cutoffs?
- The calculator gives an accurate chronological age, but legal or school cutoff rules vary by institution and region — always confirm the exact cutoff date policy with the relevant institution.