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Date & Timeage

Age Calculator

Age in years, months and days, with the next birthday and the day of the week. It borrows the way people do when counting rather than dividing days by 365.25, which drifts and produces a fraction nobody uses.

Also called: how old am i, age in days.

Also show
Age
36 years, 2 months and 2 days

36 years, 2 months and 2 days. That is 13,212 days, or 434 whole months. The next birthday is 2027-06-15, a Tuesday, in 302 days. Computed at UTC midnight, so a daylight saving change cannot shift the day count.

Total days
13,212
Whole months
434
Whole weeks
1,887
Hours
317,088
Days to the next birthday
302
Next birthday
2027-06-15
Falls on a
Tuesday
Born on a
Friday
Next day milestone
14,000
Milestone date
2028-10-13
Detail
The next birthday is 2027-06-15, a Tuesday, in 302 days.
On leap years
Computed at UTC midnight, so a daylight saving change cannot shift the day count.
How this is calculated
Method and background

How this is calculated

Subtract the date components and borrow when one goes negative: days borrow the length of the preceding month, months borrow twelve. That matches how anyone would say their age aloud, unlike dividing total days by 365.25, which gives a decimal that has to be converted back. Everything computes at UTC midnight so a daylight saving boundary cannot shift a day count. Someone born on 29 February has a birthday only in leap years, and the page says which convention it applied.

the same borrowing people do when counting aloud, which is why it matches how age is stated
d
The two dates

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a 1990 birth date

Date of birth
1990-06-15
Age on
2026-08-17
Also show
Next birthday and the day it falls on

Age36 years, 2 months and 2 days

borrowed the way age is counted aloud; 15 June 1990 was a Friday

Open this example

a leap day birth

Date of birth
2000-02-29
Age on
2026-08-17
Also show
Next birthday and the day it falls on

Age26 years, 5 months and 19 days

boundary: 2027 is not a leap year, so the convention rolls to 1 March

Open this example

Method and limits

What it assumes

  • UTC midnight for both dates, so daylight saving cannot move a result.

What it deliberately does not model

  • A 29 February birth date is treated as 1 March in common years, which is one of two conventions in use.
  • Legal age of majority follows local rules that a date difference does not capture.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Why not just divide the days by 365?
Because years are not 365 days and months are not equal. Borrowing matches how anyone would count it aloud, which is the point of an age.
When is a 29 February birthday?
In leap years it is 29 February. In common years the two conventions are 28 February and 1 March, and this page uses 1 March, which is what most jurisdictions apply for legal age.