Age Calculator
Enter your birthday to find your exact age in years, months, and days. See how many total days you've been alive, when your next birthday falls, and time between any two dates.
Background
An age calculator computes your exact age from a birth date to a target date. It counts the years, months, and remaining days — handling different month lengths and leap years. This is useful for legal age verification, medical records, retirement planning, and birthday countdowns.
This free age calculator works in your browser with zero downloads. It handles leap years correctly, counts the exact remaining months and days (not just years), and shows a countdown to your next birthday.
Enter your birthday
Pick your date of birth from the date selector. The "Calculate age as of" field defaults to today but you can set any future or past date to see how old you were or will be at that point.
How to use this age calculator
Two dates, instant age:
Enter your birthday
Pick your date of birth. The calculator accepts any date going back centuries.
Set the target date
Defaults to today. Change it to see your age at a specific past or future date.
Read your exact age
See years, months, days, total days lived, and a countdown to your next birthday.
How this age calculator works
The calculator subtracts the birth date from the target date, properly handling months with different lengths and leap years.
Formula & Equation Used
Age calculation isn't a single formula — it's a date-difference algorithm:
Try it yourself
Example Problem & Step-by-Step Solution
Someone was born on March 7, 1995. What is their exact age on August 20, 2026?
Frequently Asked Questions
How does the calculator handle leap years?
Leap years are counted correctly. February 29 birthdays are recognized. When calculating age from Feb 29 in a non-leap year, the calculator treats March 1 as the birthday boundary.
Can I calculate age between two past dates?
Yes. Set the "Date of Birth" to the start date and "Calculate age as of" to the end date. It works for any two dates — past, present, or future.
Why does my age in months not match my expectation?
Months have different lengths (28-31 days). The calculator counts a full month as passing when the same day-of-month arrives. From Jan 31 to Feb 28 is 0 months and 28 days — not 1 month — because Feb doesn't have a 31st.
Is my legal age different from my chronological age?
In most jurisdictions, your legal age changes at the start of your birthday (midnight). Some countries use different conventions. In South Korea, everyone is 1 year old at birth and gains a year each January 1st — though South Korea officially switched to the international system in 2023.
How age is measured
Age is the time elapsed since birth. Most of the world measures age chronologically — you turn 1 on the first anniversary of your birthday. But age conventions vary by culture.
Age-counting systems
Common age milestones
Age by the numbers
Age & life expectancy around the world
Japan
Nigeria
Monaco
Calculator features explained
Date of birth
Pick any date using the date picker. Works for dates going back centuries.
Target date
Defaults to today. Set a future date to see how old you'll be, or a past date to see how old you were.
Birthday countdown
See exactly how many days until your next birthday. Counts down from today automatically.
Copy results
Copy your full age breakdown to the clipboard for sharing or record-keeping.
FAQ
How do I calculate my exact age manually?
Subtract your birth year from the current year. If your birthday hasn't happened yet this year, subtract 1. For months and days, count from your last birthday to today.
How many days are in a year?
365 days in a regular year, 366 in a leap year. Leap years occur every 4 years, except for years divisible by 100 (unless also divisible by 400). So 2000 was a leap year, but 1900 was not.
What day of the week was I born on?
Enter your birth date in the calculator, then check the day. January 15, 1990 was a Monday, for example. The calculator uses the Gregorian calendar which accounts for all date rules.