Age Calculator
Enter a date of birth to find the exact age in years, months and days — plus the total number of days, the day of the week you were born, and the next birthday.
How the age calculation works
Age is counted on the calendar, not by dividing days by 365. First, the calculator counts whole years back to the most recent birthday. Then it counts whole months since that birthday. The remaining days are what is left over.
Because months have different lengths — 28 to 31 days — the calculator borrows days from the previous month when needed, the same way you would work it out on paper. For example, from 15 October to 14 November is 30 days, because October has 31 days.
Leap years are handled automatically. A leap year has 366 days, with 29 February added. A year is a leap year if it is divisible by 4, except century years, which must be divisible by 400. So 2024 is a leap year, 2023 is not, and 2000 was a leap year.
Worked example
Someone born on 15 June 1990. On 14 November 2026, their age is 36 years, 4 months and 30 days. Step by step:
- 15 June 1990 to 15 June 2026 is 36 full years.
- 15 June 2026 to 15 October 2026 is 4 full months.
- 15 October 2026 to 14 November 2026 is 30 days (October has 31 days).
In total, that is 13,301 days. Their next birthday is 15 June 2027, which is 213 days after 14 November 2026.
Frequently asked questions
Does the calculator handle leap years?
Yes. All calculations use the real calendar, so leap days are counted exactly. Someone born on 29 February 2000 turned 26 on 1 March 2026, because 2026 is not a leap year and has no 29 February.
What if I was born on 29 February?
Your birthday only appears on the calendar every four years. This calculator counts your next birthday as 28 February in other years, and your age in full years increases on 1 March. Some people celebrate on 28 February and some on 1 March — both are common.
Why does the calculator ask for an "age at" date?
It defaults to today, but you can change it to work out an age on any date — for example, how old someone was on their wedding day, or how old a child will be on the first day of school.
Why count months instead of just dividing days by 30?
Because months are not all the same length. Dividing by 30 would give a wrong answer in most cases. Counting whole calendar months, then the leftover days, matches how age is normally understood.
Is my date of birth stored anywhere?
No. The calculation runs entirely in your browser. Nothing you enter is sent to a server, stored, or shared. See the Privacy Policy.
Related tools
- Days Between Dates — count the days between any two dates.
- Days Until — Countdown — count down to a birthday or holiday.
- Day of the Week — find the weekday of any date.
- Add or Subtract Days — what date is N days from now?