D-Day Calculator
FAQ
How is it calculated?
The number of days from the base date to the target date. A future target shows D-N, a past one D+N, and the same day D-Day.
What does "Count first day" do?
It counts the first day as day 1. Jan 1 to Jan 10 is 9 days without it and 10 days with it — use it for anniversaries counted from day 1.
Can I change the base date?
Yes. It defaults to today; change it to count from another date.