Age Calculator
Enter a date of birth to see the exact age in years, months, and days — plus a few extra facts.
| Age | Approx. Days Lived | Approx. Weeks Lived |
|---|---|---|
| 10 years | 3,653 | 522 |
| 20 years | 7,305 | 1,044 |
| 30 years | 10,958 | 1,565 |
| 40 years | 14,610 | 2,087 |
| 50 years | 18,263 | 2,609 |
| 60 years | 21,915 | 3,131 |
| 70 years | 25,568 | 3,653 |
| 80 years | 29,220 | 4,174 |
FAQ
How is exact age calculated?
Age is calculated by counting full years, months, and remaining days between the date of birth and the target date, accounting for varying month lengths and leap years — not just subtracting birth year from the current year.
Why might my age differ from a simple year subtraction?
Subtracting birth year from the current year gives the wrong answer before your birthday has happened yet in the current year, since a full year hasn't actually passed. This calculator accounts for whether the birthday has occurred yet.
Does this account for leap years?
Yes — the calculation is based on actual calendar dates, so leap years (and the extra day in February) are automatically factored into the day and week counts.
What is this useful for?
Common uses include checking eligibility ages for school, work, or legal requirements, working out exact age for medical or legal forms, or just satisfying curiosity about milestones like your 10,000th day alive.
How many days old am I at 30, 40, or 50 years old?
Using a 365.25-day average year to account for leap years, 30 years old works out to about 10,958 days (roughly 1,565 weeks), 40 years old to about 14,610 days, and 50 years old to about 18,263 days. Enter your own birth date above for an exact, calendar-accurate figure.
What is a 'milestone' age in days, like turning 10,000 days old?
Turning 10,000 days old (about 27 years and 4 months) is a popular milestone people like to mark, similar to a round-number birthday. Other commonly celebrated day-count milestones include 1,000 days, 5,000 days, and 20,000 days old.
How accurate is a days-lived total compared to counting every single day?
The total shown above uses your exact birth date and today's date, so it accounts for every actual leap year in your lifetime rather than an average — it's precise to the day, not an estimate.
How old will I be on a future date?
Enter your date of birth and set the 'As of' field to the future date. The result shows your age in years, months and days on that day.
How do I find how old someone was on a past date?
Enter their date of birth and set 'As of' to the date of the event. This works for historical dates as well, as long as both dates are entered as calendar dates.
How does the calculator treat a 29 February birthday?
In years that are not leap years it counts 28 February as the birthday, so someone born on 29 February 2000 is 26 years old on 28 February 2026 in this calculator. Local law may use 1 March instead.
About this tool
This calculator works out exact age in years, months, and days between any two dates, along with total days and weeks lived and a countdown to the next birthday. Everything runs instantly in your browser — no sign-up, no data stored.
Worked example
Take a date of birth of 15 March 1990 and an "as of" date of 20 October 2026. The calculator counts whole months since the birth date, which gives 36 years and 7 months, and then counts the 5 days since the most recent monthly anniversary (15 October). The age is 36 years, 7 months and 5 days. The two dates are 13,368 days apart, which is 1,909 full weeks, and the next birthday is 146 days away.
Leap days and end-of-month birthdays
Birthdays on the 29th, 30th or 31st do not exist in every month, so calculators have to make a choice. This one uses the last day of the month when the birth date does not exist:
| Date of birth | As of | Result | Days to next birthday |
|---|---|---|---|
| 2000-02-29 | 2026-02-28 | 26y 0m 0d | 365 |
| 2000-02-29 | 2026-03-01 | 26y 0m 1d | 364 |
| 1995-01-31 | 2026-02-28 | 31y 1m 0d | 337 |
| 1995-01-31 | 2026-03-01 | 31y 1m 1d | 336 |
A person born on 29 February is treated as having their birthday on 28 February in years that are not leap years. Legal systems differ: some use 28 February and others 1 March, so check the rule that applies to you if the exact day matters.
Milestone days
Some people like to celebrate days lived and not years. Counting calendar days from 1 January 2000:
| Milestone | Date reached | Age in years (approx.) |
|---|---|---|
| 1,000 days | 27 September 2002 | 2.7 |
| 5,000 days | 9 September 2013 | 13.7 |
| 10,000 days | 19 May 2027 | 27.4 |
| 15,000 days | 25 January 2041 | 41.1 |
| 20,000 days | 4 October 2054 | 54.8 |
Enter your date of birth and the date of a milestone as the "as of" date to check it for yourself.
When an exact age is useful
- Eligibility and cut-off dates. School starting age, sports categories and insurance products often depend on age on a particular day.
- Retirement and pension planning. Set the "as of" date to a future date to see how old you will be then.
- Legal ages. Voting, driving, drinking and contract ages are set by local law, so use the calculator as a check and confirm the rule that applies.
- Records and family history. Set the "as of" date in the past to find how old someone was at an event.