Introduction
This Birthday Calculator tells you exactly how old you are and when your next birthday comes. Type in your date of birth, and it shows your age in years, months, days, weeks, hours, minutes, and seconds. It works much like a dedicated Age Calculator, but with birthday extras built in.
It also shows the day of the week you were born, how many days are left until your next birthday, and the dates of your next six birthdays. You can see big milestone birthdays too, like turning 18, 30, 50, or 100, and what weekday each one lands on.
There is more than just age. The tool gives your zodiac sign, Chinese zodiac animal, Celtic tree sign, birthstone, birth flower, and birth colors. It adds fun facts like your heartbeats so far, hours slept, full moons seen, and your age on Mars, Jupiter, and other planets.
You can also pick any "as of" date to find your age on a past or future day, or compare your birth date to famous events. Every answer comes with a clear step-by-step solution, so you can see how the math works.
How to use our Birthday Calculator
Enter your birth date and pick the date you want to measure from. The birthday calculator shows your exact age, your next birthday, your zodiac signs, birthstones, life path number, fun life stats, and your age on other planets.
Month: Pick the month you were born in from the drop-down list.
Day: Pick the day of the month you were born. The list changes to match the month and year you chose.
Year: Pick your birth year. You can choose any year from 1900 up to this year.
Calculate As Of Date: This is set to today. Change it to any past or future date to see how old you were, or will be, on that day.
Custom Date to Compare: Optional. Add any date you care about, like a wedding or a trip, and we show your age on that day in the notable dates table.
Hemisphere: Choose Northern or Southern. This tells us which season you were born in.
Calculate: Click this button to see your results. Click Reset to clear your entries and start again.
What This Birthday Calculator Explains
Your birthday is the day and month you were born. Each year, when that date comes around again, you turn one year older. This page is about how people count age from a birth date, and what fun facts your birth date can tell you.
How Age Is Counted
Age is counted in full years since you were born. You do not turn a new age until your birth month and day come back around. For example, if you were born on June 15, 1990, you are still 35 on June 14, 2026, and you turn 36 on June 15, 2026.
Age can also be shown in smaller units. One year is about 365.2425 days, because Earth takes a little more than 365 days to go around the Sun. That extra bit is why we add a leap day (February 29) every four years. Days can be changed into weeks, hours, minutes, and seconds by simple multiplying:
- 1 day = 24 hours
- 1 hour = 60 minutes
- 1 week = 7 days
Leap Day Birthdays
People born on February 29 only get their real date every four years. In other years, most calendars and rules move the birthday to March 1 (or sometimes February 28). These babies are often called "leaplings."
Why Your Birthday Weekday Changes
A year has 365 days, which is 52 weeks plus 1 extra day. So your birthday usually moves ahead one weekday each year. After a leap day, it jumps ahead two weekdays. That is why your birthday lands on a weekend some years and a school or work day in others. You can check any single date with the Day Of The Week Calculator.
Birth Signs and Symbols
Many cultures link birth dates to signs and symbols:
- Western zodiac: 12 sun signs based on the month and day, like Leo or Pisces.
- Chinese zodiac: 12 animals that repeat every 12 years, like Rat, Ox, or Tiger.
- Celtic tree signs: 13 tree names tied to parts of the year.
- Birthstones and birth flowers: one gem and flower for each month, such as Ruby for July.
These are traditions, not science, but they are a fun part of birthdays.
Life Path Number
In numerology, people add up all the digits of a birth date, then keep adding until one digit is left (11, 22, and 33 are kept as they are). That number is called the Life Path number. It is just for fun.
Age on Other Planets
A "year" is the time a planet takes to circle the Sun. Mercury takes only about 88 Earth days, so you would be much older there. Neptune takes about 165 Earth years, so almost nobody reaches age 1. To find your age on a planet, divide your total days lived by that planet's orbit length in Earth days.
Fun Day Milestones
Some people mark special day counts instead of birthdays, like 1,000 days, 7,000 days (1,000 weeks), 10,000 days, or 1 billion seconds old (about 31.7 years). These are easy to work out once you know your total days lived.