Of course, when you know the start and end dates for an event, you can use a precise version How many days are there between two dates? or Days between dates. The historical version..
But this one might be useful when you see or hear questions like this:
- "13000 days in years?"
- "how many years are in 20000 days?"
or sentences like that:
- "I am 10000 days old."
- "The siege was lifted after 872 days after it began" (Siege of Leningrad).
Naturally, you want to get a general sense of time, length of a period in general, and you don't care if it is plus one day or minus one day because of a leap year or starting month.
In this case, you can use the calculator below. It just adds the specified number of days to the 1st of January 2017 (the first non-leap year after 2016) and then grabs a number of years, months, and days in the month passed between start and end date. This allows you to make sense of the number of days and understand how many years, months, and days it takes.