What is an age calculator?
An age calculator is a tool that precisely determines your age based on your date of birth. The result is displayed in years, months and days, along with the total number of days, weeks and months since birth.
How do you calculate age from date of birth?
Enter your date of birth and, optionally, a target date. If no target date is entered, the calculation uses today's date. The calculator computes the difference between the two dates and presents your exact age along with additional statistics.
What is the age calculation formula?
Age is calculated by subtracting the birth date from the target date. First, complete years are determined, then remaining months, and finally the remaining days. The total number of days is computed by counting all days between both dates, including leap years.
What are some age calculation examples?
If you were born on March 15, 1990, and today is July 20, 2025, your age is 35 years, 4 months and 5 days. That corresponds to more than 12,900 days since birth.
Are age calculation systems different across cultures?
Most countries use the Western system, where a person turns 1 on their first birthday after birth. Some East Asian cultures traditionally used a system where people are born already age 1 and gain a year at the new year rather than on their birthday — meaning two people born at different points in the same year could be considered the same age. South Korea officially switched to the Western system in 2023. This calculator uses the standard Western method. For other date calculations, our date calculator can find the difference between any two dates.
How many days until my next birthday?
The calculator automatically computes how many days remain until your next birthday and shows the exact date of your upcoming birthday.
How does a leap year affect age calculation?
Leap years add an extra day (February 29) every four years, which affects the total days count. People born on February 29 typically celebrate their birthday on February 28 or March 1 in non-leap years. The calculator handles this automatically.