Math & Dates Age calculator
Find an exact age in years, months and days from any date of birth, plus the total in weeks, days and hours and the countdown to the next birthday.
Defaults to today. Change it to age at any date.
Age
31 y · 2 m · 26 d
11,410 days since June 15, 1995.
- In months
- 374
- In weeks
- 1,630
- In days
- 11,410
- In hours
- 273,840
- Next birthday
- 278 days
- Turning
- 32
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Reembun. (2026, July 27). Age calculator. https://reembun.com/age-calculator
How to use it
Enter the date of birth
Type it or pick it from the date field. The age appears as soon as the date is complete.
Choose the date to measure to
Age at this date starts on today. Change it to work out an age at any past or future date, such as a deadline or an eligibility cut-off.
Read the breakdowns
The headline is years, months and days. Underneath, the same age appears in months, weeks, days and hours, with the next birthday.
Take the numbers with you
Use Share result above the steps to capture the figures as text for a form or a message.
How exact age is worked out
Age is not simply the difference in days divided by 365.25. That produces answers people find wrong, because human age is a calendar quantity. This calculator works the way you would count on your fingers:
- Subtract the birth year from the target year.
- Subtract the birth month from the target month.
- Subtract the birth day from the target day.
- If the day result is negative, borrow the number of days in the month before the target date, and reduce the month count by one.
- If the month result is negative, borrow twelve months and reduce the year count by one.
Because step 4 borrows the actual length of the preceding month, the result respects both leap years and the irregular length of February.
A worked example
Born 15 June 1995, measured on 27 July 2026:
- Years: 2026 − 1995 = 31
- Months: 7 − 6 = 1
- Days: 27 − 15 = 12
The answer is 31 years, 1 month and 12 days, which is 11,365 days in total, or 1,623 complete weeks.
Now take a case that needs borrowing. Born 31 March 2000, measured on 30 June 2026: the day difference is 30 − 31 = −1, so borrow the 31 days of May, giving 30 days, and reduce the month count from 3 to 2. The answer is 26 years, 2 months and 30 days.
Total days, and why they differ from years × 365
Between 15 June 1995 and 27 July 2026 there are eight leap days (1996, 2000, 2004, 2008, 2012, 2016, 2020, 2024). Multiplying 31 years by 365 gives 11,315 days; the true count is 11,365. Over a lifetime the drift adds up to weeks, which is why the exact day count is worth having when eligibility or a contract turns on it.
Leap year rules
A year is a leap year if it is divisible by 4, except centuries, unless the century is divisible by 400. So 1900 was not a leap year and 2000 was. This is the Gregorian correction, and it keeps the calendar aligned with the solar year to within one day per 3,030 years.
Common uses
- Eligibility. Confirming an exact age on a specific date for a licence, contract, pension or school admission.
- Milestones. Finding the date you turn 10,000 days old, or how many days remain until a birthday.
- Records. Establishing the precise interval between two events for a form that asks for years and months rather than a total.
Common questions
Why does the answer differ from other age calculators?
The usual cause is how months are borrowed. This calculator borrows the actual length of the preceding month, so 31 January to 1 March gives 1 month and 1 day in a non-leap year. Tools that assume every month is 30 days will report something slightly different. Calendar arithmetic has no single correct convention, so precise day counts are more reliable for comparison.
How is age counted for someone born on 29 February?
Legally this varies by jurisdiction. Most common-law countries treat the birthday as 1 March in non-leap years, while some civil-law systems use 28 February. This calculator rolls forward to 1 March when looking for the next birthday, which matches the more common convention.
Can I work out my age on a past or future date?
Yes. Change the second date to any date you like. It is useful for eligibility questions: establishing whether someone was 18 on a specific date, or how old they will be when a policy matures.
Does this account for time zones?
Dates are interpreted in your device's local time zone with no time component, which is how legal ages are normally reckoned. If you were born in a different time zone than the one you are in now, the calendar date on your birth certificate is the one to enter.
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