How D-day is counted
The target date is D; days before are shown as D−number and days after as D+number. If today is the target date, it's D-day.
Anniversaries count the first day
For relationship anniversaries or a baby's 100th day, the start day usually counts as day 1. So the 100th day is 99 days after the start. "N days later", on the other hand, doesn't include the start day. This calculator supports both.
When to use it
- Days left until an exam, discharge or due date
- Days since you started dating or got married
- Contract periods and vacation days
FAQ
Is the last day included in the days between two dates?
By default it's the difference between the start and end dates. Choose "Include both end dates" to add 1 day.
When is a baby's 100th day?
Counting the birth date as day 1, it's the 100th day — 99 days after birth.