Calculate Year of Birth, Age and Time Passed

Calculator for the year of birth, the exact age and for the time that has passed since a specific date. As a reference date, the current date is preset, this can be changed at will.

Reference date: . . , : o'clock

Calculate year of birth from age and date of birth:
Enter the age at the reference date and the birthday, the year of birth will be calculated.

Age at deadline: years | Month of birth: Day of birth:

The year of birth is

Calculate your exact age or the time since a certain date:
Enter date and time from the past, the time span to the reference date will be calculated.

Month: Day: Year: Hour: Minute:

Time past until reference date:

On these pages you will find several calculators on the topics of birthdays, ages, years, months and days, each for different applications. Calculating with such times is not complicated, but tedious, and this is intended to be simplified here.

To explain the basics of the times of the year: the earth rotates around the sun in a year. On the same date every year, whether it is a birthday or not, the earth is in the same place on its orbit. However, not at the same time of day, as not a whole number of days fit into a year. A day is the time in which the earth rotates around its own axis. A year has a little more than 365 days, the time it takes for the earth to return to the position of the previous year is 365 days, 5 hours, 48 minutes and 45 seconds. Therefore, the earth always "looks" in a different direction at the same point in its orbit in different years. The month is originally based on the moon, which in turn does not correspond in whole numbers to days and years. Due to different month lengths and a whole number of days per month (28 to 32) and months per year (12, of course), the month is more intuitive to use, but is now decoupled from the moon.