Date and time
Age calculator
Calculate exact years, months, and days, days lived, and time until your next birthday using an editable reference date.
Main calculation
How old am I?
Enter a birth date. The reference date defaults to today, but you can change it to calculate an age in the past or future.
Only affects birth dates on February 29.
Age in other units
Hours, minutes, and seconds are approximate because this version uses dates without times.
How it is calculated
Age is not calculated by simply subtracting years. The calculator counts complete years, then complete months, and finally the remaining days based on each month's actual length.
January 1 to January 2 is one day lived. Inclusive counting is not used.
February 29
If you were born on February 29, in non-leap years you can use February 28 or March 1 as your birthday reference. The calculator lets you choose the rule so the result is explicit.
For official procedures, schools, or requirements, always confirm the exact rule with the relevant institution.
Notice
This calculator uses calendar dates to help estimate age, days lived, and upcoming birthdays. For official, school, medical, or legal requirements, always confirm the exact rule with the relevant institution.
Frequently asked questions
How is exact age calculated?
It is calculated using calendar dates: complete years are counted first, then complete months, and finally the remaining days between the birth date and reference date.
How many days have I lived?
Days lived are the difference between the birth date and reference date. The count is not inclusive: January 1 to January 2 is one day.
What if I was born on February 29?
In non-leap years, you can choose whether to use February 28 or March 1 for the next birthday. The calculator uses February 28 by default.
Are the hours, minutes, and seconds exact?
They are approximate because this version only asks for a date, not a birth time. They are calculated from the start of the birth date to the start of the reference date.
Can I calculate how old I will be on a future date?
Yes. Set the reference date to a future date and the calculator will show your age on that day.
Can I use it for official purposes?
It is a calculation aid, but each school, institution, or procedure may have its own rules. Always confirm the applicable official criteria.