Days Between Dates

Pick two dates. By default the count excludes the end date, which is how elapsed time is usually measured.

Count days

Enter your values and select Calculate to see the result.

Inclusive or exclusive?

From Monday to Friday of the same week is 4 days of elapsed time, but 5 days if you count both Monday and Friday — for example the days of a conference. Tick “include the end date” for the second kind of count.

Worked example

1 March to 31 March

  1. Elapsed days: 31 − 1 = 30
  2. Counting both the first and the last day: 30 + 1 = 31

30 days between them; 31 days inclusive.

How it is calculated

Each date is converted to a serial day number (days since a fixed epoch in the proleptic Gregorian calendar), and the two numbers are subtracted. This handles leap years and months of different lengths exactly, and gives the same result whichever date you enter first.