Age Calculator
Calculate an exact age in years, months and days from a date of birth.
Default: today.
Enter a date of birth to calculate the corresponding age.
How is this result calculated?
Age is calculated in completed years, months and days, never as a simple day difference divided by 365: years are compared first, then months, then days between the date of birth and the reference date. If the day of the reference date is earlier than the day of birth, a full month is borrowed (whose exact length — 28, 29, 30 or 31 days — depends on the month and on leap years); if the resulting month is negative, a full year is then borrowed in turn.
The total number of days lived is a raw calendar-day difference between the two dates. The next birthday date is determined from the day and month of birth applied to the year of the reference date (or to the following year if that date has already passed), and the countdown corresponds to the number of days remaining until that date.
Frequently asked questions
Why not simply divide the number of days by 365?+
Dividing by 365 (or 365.25) gives only a rough estimate, since months don't all have the same length and one year in four has 366 days. This calculator counts the actual completed years, months and days, the way you would by hand with a calendar.
How is February 29 handled?+
For someone born on February 29, the birthday naturally falls on March 1 in non-leap years (since February then only has 28 days), and returns to February 29 in leap years.
Can I calculate an age at a past or future date?+
Yes: the reference date isn't fixed to today. By changing it, you can find the exact age a person had on a past date, or will have on a future date.
What's the difference between legal age and exact age?+
Legal age (used for adulthood, retirement, etc.) corresponds to the number of birthdays already passed, i.e. the exact age in whole years calculated here. Exact age additionally breaks down the months and days elapsed since the last birthday.
What is the total number of days lived useful for?+
It's the raw number of days elapsed since birth, without splitting into years/months. It's sometimes requested for administrative purposes, or simply out of curiosity to know an exact total, for example to mark a round number like the 10,000th day of life.