Age Calculator
Enter a birth date to find the exact age in years, months and days as of today, or as of any date you choose.
Your exact age is the time from your birth date to today, expressed in years, months and days. Count the whole years first, then the leftover months, then the remaining days, borrowing from the calendar when a day or month comes out negative. From 15 May 1990 to 20 May 2024 is 34 years, 0 months and 5 days.
How to Use This Calculator
Pick the birth date in the first field. Leave the second field blank to calculate age as of today, or choose a date to find how old someone was (or will be) on that specific day — handy for working out an age at a past event or on a future birthday. The calculator returns the exact age in years, months and days, plus the total number of days.
Because it defaults to today's date, the age updates automatically each day. Both fields use your device's date picker, so there is no ambiguity about day-versus-month order.
How the Calculation Works
The calculator counts down the calendar in three steps. It first takes the difference in years, then in months, then in days. If the day difference is negative, it borrows the number of days in the preceding month and reduces the month count by one; if the month difference is then negative, it borrows twelve months and reduces the year count by one. This borrow logic is why age accounts correctly for months of different lengths and for leap years. The total-days figure is computed separately as the raw number of calendar days between the two dates.
Worked Example
Take a birth date of 15 May 1990 and a reference date of 20 May 2024. Years: 2024 − 1990 = 34. Months: May − May = 0. Days: 20 − 15 = 5. No borrowing is needed, so the age is exactly 34 years, 0 months and 5 days. The total elapsed time is 12,424 days, or about 1,774 weeks. If the reference date were 10 May 2024 instead, the day difference (10 − 15) would be negative, so the tool would borrow April's 30 days and report 33 years, 11 months and 25 days.
What the Result Means
The years-months-days figure is the everyday way we state age, and it is exact for the calendar. The total-days number is useful for milestones (a 10,000-day birthday), for precise interval calculations, and for any situation where whole years are too coarse. Note that age in years alone can be misleading near a birthday — someone can be 'in their 34th year' while still counting as 33 — which is why the month and day breakdown is often more informative.
Assumptions and Limitations
The calculator uses calendar dates and your local interpretation of 'today,' so results can shift by a day across time zones right around midnight. The years-months-days breakdown follows the common borrow convention; because months vary in length, a month-based breakdown of the same interval can differ by a day from other conventions, though the total-days figure is unambiguous. Very end-of-month birth dates (like the 31st) can produce edge cases where the month count is one different from what you might expect.
Who Uses an Age Calculator
Anyone needing an exact age uses this — for forms, eligibility checks, milestones, or simple curiosity. Run it to get an age in years, months, and days as of today or any date, or to work out an age at a past or future event. Enter a birth date to see the precise age and total days.
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Open calculator →Frequently Asked Questions
How do I calculate someone's exact age?
Subtract the birth date from the target date in years, then months, then days, borrowing from the calendar when needed. This tool does it automatically and also shows the total days lived.
Does the age update every day?
Yes. If you leave the second date blank, the calculator uses today's date, so the age increases by a day each day and turns over on the birthday.
Can I find my age on a past or future date?
Yes. Enter that date in the second field. The tool will calculate how old someone was on a past date or will be on a future one, such as an upcoming birthday.
How does the calculator handle leap years?
It counts real calendar days, so leap days are included automatically in the total-days figure, and the month borrow uses the actual length of each month, including February in leap years.
Why is my age in months not just years times 12?
Because the months and days are the remainder after the whole years, not a re-expression of them. The breakdown tells you how far past your last birthday you are, in months and days.
What is my age in total days?
It is the raw count of calendar days from your birth date to the reference date, shown alongside the years-months-days result. It is the most precise single number for age.
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