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Age Calculator

Enter your date of birth to see how old you are in years, months and days, the day of the week you were born on, and how long you have been alive.

Your date of birth

Your age
Enter your date of birth to see your age

How to use this calculator

  1. Enter your date of birth in the date field, in day/month/year order.
  2. Your age appears straight away as years, months and days, with the figures picked out in orange.
  3. Below it, a line shows how many days are left until your next birthday.
  4. Use Reset to clear the field and start again.

A date in the future, or one before 1 January 1900, shows a short message instead of a result.

How is age calculated in years, months and days?

Age is a calendar difference, not a total divided into equal chunks. The calculator works through the three units in turn and borrows from the next unit up whenever a figure comes out negative:

years · months · days = today − date of birth, unit by unit
  • Subtract the years, the months and the day-of-month separately.
  • If the days are negative, add the length of the previous calendar month and subtract one month.
  • If the months are then negative, add 12 and subtract one year.

Example: born 15 June 1990, with today being 10 September 2024. The years are 2024 − 1990 = 34. The months are September − June = 3. The days are 10 − 15 = −5, so borrow the length of August, 31 days: 31 − 5 = 26 days, and the months drop from 3 to 2. The result is 34 years, 2 months and 26 days.

How many days until my next birthday?

The calculator puts the day and month of your birth onto the current year. If that date is still ahead, it counts the whole days from today to it. If it has already gone by, it counts to the same date next year instead. On your birthday the figure is zero, and the line reads that your next birthday is today.

What day of the week were you born?

Once you enter your date of birth, the calculator names the weekday it fell on — a Monday, a Tuesday, and so on — directly beneath your age. It reads the day straight from the calendar, the same way it counts the months and days of your age, so it stays correct for any date back to 1900.

How long have you been alive?

The you've been alive for table restates your age in five units at once:

  • Months — your age in whole calendar months.
  • Weeks — the whole weeks since your birth, with any leftover days noted.
  • Days — the exact number of days from your date of birth to today.
  • Hours and minutes — the day count multiplied by 24 and by 1,440. These assume a birth at midnight, because the calculator does not ask for a time of birth.

What about people born on 29 February?

A leap day only comes round every four years. In the years in between, this calculator treats a 29 February birthday as falling on 28 February — for both the age breakdown and the countdown, so the two stay consistent. Someone born on 29 February 2000 therefore turns 23 on 28 February 2023, while in a leap year such as 2024 their birthday lands on 29 February as normal.

Frequently asked questions

How do you calculate age in years, months and days?

Start with the difference between today and the date of birth in each unit: years, then months, then days. If the day figure is negative, borrow the length of the previous calendar month — its real length, not a flat 30 — and take one off the months. If the months figure is then negative, borrow 12 months and take one off the years. The result is a true calendar age, which is why it does not match dividing the total days by 365.

How is the "days until your next birthday" figure worked out?

The calculator takes the day and month of your birth, applies them to the current year, and counts the whole days from today to that date. If this year's birthday has already passed, it uses next year instead. On the day itself the figure is zero.

How does the calculator handle a 29 February birthday?

In a year that is not a leap year there is no 29 February, so the birthday is treated as 28 February. The same rule is applied to both the age breakdown and the birthday countdown, so the two never disagree. In a leap year the birthday falls on 29 February as normal.

What day of the week was I born on?

Enter your date of birth and the calculator shows the weekday just below your age — for example, someone born on 30 December 1986 was born on a Tuesday. It works this out from the calendar date itself, using the same day-numbering that drives the age calculation.

How many days, hours and minutes have I been alive?

The "you've been alive for" table converts the whole number of days since your birth into weeks, days, hours and minutes, alongside your age in calendar months. The hour and minute figures assume a birth at midnight, because the calculator does not ask for a time of birth.

Why is my age here different from my age in days divided by 365?

Dividing by 365 ignores leap years and pretends every month is the same length. Calendar age counts actual months and actual month lengths, so "1 year" always means the same date one year later, whether or not a 29 February fell in between. Over decades the divide-by-365 method drifts by several days.

What dates of birth does the calculator accept?

Any date from 1 January 1900 up to today. A date in the future is rejected, because there is no age to show, and a date before 1900 is rejected as almost certainly a typo. Both cases show an inline message rather than a result.

Is my date of birth sent anywhere?

No. The calculation runs entirely in your browser. Nothing is submitted, stored or logged, and the page makes no network request when you enter a date.