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- Enter your date of birth to see how old you are in years, months and days.
- You also get your next birthday countdown, total days, weeks, hours and minutes.
- Fun extras: star sign, birthstone, generation, your age on other planets and your next 1,000-day milestone.
- Change the Age as of date to see how old you were, or will be, on any day.
How to use the age calculator
Enter your date of birth
Pick the day, month and year you were born, or type the date in.
Leave the date as today
The Age as of box starts on today, so the answer to how old am I appears at once.
Read your age
The main result shows your age in years, months and days, with the weekday you were born.
Explore the extras
Scroll down for the birthday countdown, total time lived, star sign, planet ages and milestone dates.
How old am I? How age is counted
Age is counted on the calendar, not by dividing days by 365. First count the full years since the birth date. Then count the full months after the most recent birthday. The days left over are the last part. A person born on 15 May turns a year older every 15 May, whatever the length of the year.
The age steps
Years = full birthdays that have passed
Months = full months since the last birthday
Days = leftover days after those months
Total days = as-of date − date of birth
The calculator works with plain calendar dates, so time zones never shift the result by a day.
Worked examples
Example 1: an adult
Born 15 May 1990. Age on 24 October 2026.
The next birthday is the 37th.
Example 2: a leap-day birthday
Born 29 February 2000. Age on 28 February 2026.
2026 is not a leap year, so the birthday falls on March 1.
Example 3: a short gap
Born 31 January 2024. Age on 1 March 2024.
When a month is shorter, the calendar uses its last day. One month after January 31 is February 29, and March 1 is one day later.
Fun facts the calculator adds
Along with your exact age, the calculator shows a few things people like to know. Treat them as entertainment, not science.
For the person born 15 May 1990
Shown for 24 October 2026.
A billion seconds is 11,574 days, about 31.7 years.
Age milestones in days
Roughly how many years
Based on an average year of 365.2425 days.
The exact day moves a little depending on the leap years you have lived through.
Where an age calculator helps
Forms and applications
Get your exact age for school, sports, travel or insurance forms.
Birthday planning
See how many days are left and which weekday your birthday falls on.
Family history
Work out how old someone was on a past date, such as a wedding or a move.
Planning ahead
Set the as-of date in the future to see how old you will be at an event. To compare two people, use the age difference calculator.
This tool gives a calendar age. For contracts, benefits or other official needs, follow the rules of the organization involved, because some use fixed cut-off dates. Star signs use common date ranges that can shift by a day between sources.
Age calculator FAQ
How old am I?
Enter your date of birth and keep the Age as of date on today. The result shows your age in years, months and days.
How do you calculate age?
Count the full years from the birth date to the as-of date, then the full months, then the remaining days. This calendar method matches how birthdays work.
How do I find my age on a past or future date?
Change the Age as of box to the date you want. The result then shows your age on that day.
How is a leap-day birthday counted?
In years that are not leap years, this calculator counts your birthday on March 1. In leap years it falls on February 29.
How many days old am I?
The Total days result counts the days from your date of birth to the as-of date. A person born on 15 May 1990 has lived 13,311 days by 24 October 2026.
How is my age on other planets worked out?
Your age in Earth days is divided by the number of Earth days the planet takes to orbit the sun, for example about 687 days for Mars.