The average human lifespan is about 28,000 days. That means today represents 0.0036% of your life! Yikes... in that case, let's make this Excel mumbo jumbo quick so you can get back to the Big Stuff.
Excel gives us two ways of finding the number of days between dates.
The first method is the DAYS() function, which takes an end date and a start date and spits out the number of days between them.
The second method is simple subtraction. Remember, Excel stores dates as the number of days elapsed since January 0, 1900. Therefore, when we subtract dates, we're really subtracting a lesser serial number from a greater one, leaving us the number of days in between!