Age Calculator
Find your exact age in years, months and days from your date of birth, plus total weeks and days lived and a countdown to your next birthday.
This age calculator gives your age in completed years, months and days using a calendar-month convention with month-end clamping. It also shows how many months, weeks, days and hours you have been alive, the date of your next birthday and the weekday you were born on. Change the second date to find someone’s age on a past or future day, such as a school cut-off or a retirement date.
How to use this tool
- Enter the date of birth.
- Keep "Age on this date" as today, or choose another date.
- Read your age in years, months and days, then the totals and the birthday countdown.
- Check the milestone table for dates like your 10,000th day.
Formula
Age = whole months from birth date to target date, split into years (÷ 12) and months, plus the leftover days
Whole months are counted by adding each candidate month count directly to the birth date without passing the target date. When a month has no matching day (for example, the 31st), the last day of that month is used. Total days is the plain calendar-day difference, so leap years are included automatically.
Example
Someone born on 15 June 1990 is, on 29 October 2026, 36 years, 4 months and 14 days old. That is 436 full months, 13,285 days (1,897 weeks and 6 days) and about 318,840 hours. They were born on a Friday, and their next birthday, 15 June 2027, is 229 days away.
Frequently asked questions
How is age calculated in years, months and days?
First count the completed years, then the completed months since the last birthday, then the days left over. Someone born on 31 January turns one month old on 28 February in a common year, because February has no 31st.
How are leap-day birthdays handled?
People born on 29 February are treated as having their birthday on 28 February in common years. Some laws use 1 March instead, so check the rule that applies if the exact day matters legally.
Does the time of birth matter?
Not for the years, months and days shown here. The hours figure assumes birth at midnight, so it can be off by up to 24 hours.
Can I calculate age on a future date?
Yes. Set "Age on this date" to any later day to see how old someone will be then, for example on the first day of school.
Last updated: 2026-10-30