How to use the age calculator
- Pick the date of birth.
- "Age on" defaults to today. Change it to calculate age on any other date.
- Results update instantly: exact age, totals, the weekday of birth and days until the next birthday.
Common uses
- Forms and applications — school admissions, visas, sports leagues and exams often require age on a specific cut-off date.
- Retirement and pensions — check exactly when you reach a qualifying age.
- Milestones — find when you turn 10,000 days old (about 27 years 4 months) or 1,000 weeks.
- Genealogy — work out how old an ancestor was at a historical event.
- Pets and kids — track ages in months and weeks for vaccinations and development milestones.
Why age is trickier than it looks
Subtracting birth year from the current year only works after your birthday has passed this year. Months also have different lengths — 28, 29, 30 or 31 days — so "1 month" after 31 January is not a fixed number of days. This calculator follows the calendar method used on official documents: it counts complete years first, then complete months after the last birthday, then the remaining days. Leap years are handled automatically, including birthdays on 29 February.
Age around the world
Most countries use the "international" system, where you are 0 at birth and add a year on each birthday. Historically, some East Asian age systems counted a baby as 1 at birth and added a year every Lunar New Year. South Korea officially standardized on international age for legal purposes in 2023. This calculator uses the international system.
Planning finances around a milestone birthday? See how savings could grow with the Compound Interest Calculator.
Frequently asked questions
How is exact age calculated?
We count full years between the two dates, then full months after the last birthday, then the remaining days. This matches how age is counted on official documents.
What if I was born on 29 February?
In non-leap years your birthday is treated as 28 February for the "next birthday" countdown, which is the most common legal convention.
Can I calculate age on a past or future date?
Yes. Change the "Age on" date to any date — useful for checking eligibility on an exam date, retirement date or event.
Is my date of birth stored?
No. Everything is calculated in your browser and nothing is saved or sent.