Age Calculator
CalculateCalculate an exact age from a date of birth in years, months, and days, plus totals in weeks, days, and hours and a countdown to the next birthday. Works for any date.
Runs entirely in your browser. Nothing is uploaded.
Exact age
31 years 1 month 15 days
373
Total months
1,624
Total weeks
11,368
Total days
272,832
Total hours
Exact age in years, months & days
Working out an age in whole years is easy; working out the exact years, months, and days is where it goes wrong, because months have different lengths and leap years break any calculation that just divides by 365.25. This calculator does calendar-accurate date arithmetic — borrowing days from the correct month — and also gives the age on any date you choose, not only today, which is what forms and applications usually need.
How to calculate an exact age
- 1
Enter the date of birth
Any date, past or recent. It is read locally in your browser.
- 2
Choose the date to measure to
Defaults to today. Change it to find out how old someone was, or will be, on a specific date.
- 3
Read the exact age
Get years, months, and days, plus totals in months, weeks, days, and hours, and how long until the next birthday.
Good to know
- Months are borrowed from the month before the later date, which is what makes the day count correct across months of 28, 30, and 31 days.
- Leap years are handled by using real calendar dates rather than an average year length, so the total day count is exact.
- A 29 February birthday rolls to the following valid date in common years, matching how most institutions treat it.
- Everything is calculated in the page, so a date of birth is never transmitted.
What people use it for
- Filling in an exact age on an application, visa, or medical form
- Working out how old someone will be on a future date
- Checking a child's age in months for a developmental or school cutoff
Frequently asked questions
How is the age calculated?+
By calendar difference, not by dividing days. Months are borrowed from the previous month of the later date, so the result is correct across months of different lengths and across leap years.
Can I find my age on a past or future date?+
Yes. The second field defaults to today, but you can set it to any date to find out how old someone was, or will be, then.
How are 29 February birthdays handled?+
The next-birthday countdown rolls to the following valid date in common years, which matches how most institutions treat a leap-day birthday.
Is my data sent to a server?+
No. Calculating an age happens entirely in your browser using built-in web APIs. Nothing is uploaded, stored, or logged.
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