Age Calculator
Age
—
Next Birthday
Enter a date of birth to see results.
What is an Age Calculator?
An age calculator computes your exact age in years, months, and days as of any date you choose. It also shows how many days remain until your next birthday. Useful for verifying ages on documents, legal contexts, or simply satisfying curiosity.
How It Works
The calculator subtracts the birth date from the reference date, accounting for month-length differences and leap years:
Example
Born on March 15, 1990, calculating age as of November 8, 2025.
- Age: 35 years, 7 months, 24 days
- Days until next birthday: 127 days
Tips
- The "Age As Of" field defaults to today but can be changed. This is useful for checking what someone's age will be on a future date.
- For legal age verification (driving, voting, contracts), always use the exact calendar date, not an approximation.
- Leap year birthdays (February 29) are handled correctly. On non-leap years, the birthday is treated as March 1.
Frequently Asked Questions
How is age calculated legally?
In most jurisdictions, you reach a given age on the anniversary of your birthday. If you were born on June 15, you turn 18 at the start of June 15, not at the specific hour of your birth. Some legal systems count the birthday itself as day one.
What about people born on February 29?
Leap year birthdays are a genuine edge case. Most countries treat March 1 as the legal birthday in non-leap years. This calculator follows that convention when computing ages.
Can I calculate someone's age on a past date?
Yes. Change the "Age As Of" field to any past date and the calculator will tell you how old someone was on that specific day. This is useful for historical research or verifying age at the time of a document.
How do I calculate age in months or weeks?
The calculator shows years, months, and days. To convert the total to months only, multiply the years by 12 and add the remaining months. For total weeks, use the date calculator and divide days by 7.