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ToolPika

Age Calculator

Enter a date of birth to get the exact age today, or change the second date to find the age on any other day.

Runs in your browser. Nothing you enter is sent to a server.

How it works

The age is counted the same way you would count it on a calendar:

  1. Years. The number of birthdays that have already happened.
  2. Months. Whole months since the last birthday.
  3. Days. The days left after the last whole month.

When the birth day does not exist in a month (for example the 31st, or 29 February), the last day of that month is used instead. So someone born on 31 January is exactly one month old on 28 February (29 February in a leap year).

The total in days is the exact number of days between the two dates, counting leap years. Weeks are that number divided by 7, with the leftover days shown separately.

Dates are handled as plain calendar days, not as times, so the result never shifts by a day because of your time zone or a daylight-saving change. The “Age on” date starts at today’s date on your device.

Examples

Date of birth Age on Age In total
15 January 1990 23 September 2026 36 years, 8 months, 8 days 13,400 days (1,914 weeks + 2 days)
4 July 1985 23 September 2026 41 years, 2 months, 19 days 15,056 days
29 February 2000 28 February 2025 25 years, 0 months, 0 days 9,131 days
31 January 2023 1 March 2023 0 years, 1 month, 1 day 29 days

In the first example, the next birthday is on Friday, 15 January 2027, 114 days later, when the person turns 37. They were born on a Monday.

Good to know

  • Age on a deadline. Many applications ask for your age “on 31 December” or “on the first day of the course”. Set the second date to that day.
  • Counting the age of something else. It works for anything with a start date: how long you have been in a job, the age of a building or how long ago an event happened.

Frequently asked questions

How is age calculated in years, months and days?

First count the whole years since the birth date, then the whole months after that, then the days left over. Someone born on 15 January 1990 is 36 years, 8 months and 8 days old on 23 September 2026.

What if someone was born on 29 February?

In years without a 29 February, this calculator treats 28 February as the birthday, so the new year of age is counted from that day. Some countries legally use 1 March instead; the difference is always a single day.

Can I calculate the age on a date in the past or the future?

Yes. Change the "Age on" date to any day. It is useful for forms that ask for your age on a specific date, or to know how old someone will be at an event.

How many days old am I?

The "In total" line shows the exact number of days between the two dates, as well as the total in months and weeks.

Why is the result different from another calculator?

Months have different lengths, so "one month" after 31 January has no single right answer. This calculator uses the end of the month when a day does not exist (31 January + 1 month = 28 or 29 February), which is the usual convention.