How exact age is worked out
Age in years alone hides a lot: two people who are both "34" can be nearly a year apart. This calculator counts complete years to the last birthday, then complete months, then the leftover days, using the real lengths of the months involved. Enter a different second date to get age on any day, past or future.
Worked example
Where exact age matters
- School admissions: England's cut-off is 1 September, so age on that date decides the school year.
- Race and sport categories: many use age on 31 December or on race day.
- Pensions and benefits: entitlements switch on at exact dates, not calendar years.
- Milestone spotting: your 10,000th day, 500th month or 40th half-birthday all fall on precise dates.
Leap years, leap days
A year is a leap year if it divides by 4, except century years, which must divide by 400. So 2024 and 2028 are leap years, while 2100 will not be. The extra day keeps the calendar aligned with the Earth's orbit, and it is why the total-days figure is not simply years times 365. Anyone born on 29 February celebrates the real date every four years; for legal age purposes in the UK, the age ticks over on 1 March in other years.
Frequently asked questions
How is exact age calculated?
The calculator counts complete years first, then complete months since the last birthday, then the days left over, borrowing from the previous month's actual length where needed. That is why the answer is precise even though months vary between 28 and 31 days.
What about people born on 29 February?
A leap-day birthday only occurs every four years. In non-leap years this calculator (like UK law for age milestones) treats 1 March as the day the age ticks over.
Can I work out age at a date other than today?
Yes. Change the second date to any date you like, past or future, and the tool shows the age on that date. This is handy for forms that ask for age on a given cut-off date, such as school admissions or race categories.
How many days old am I?
The total days figure counts every day between the date of birth and the chosen date, including leap days. Someone exactly 30 years old has lived roughly 10,957 days.
Is my date of birth stored?
No. The calculation runs entirely in your browser and nothing is sent to any server. Refreshing the page clears the dates.