Dev Inventory
Simple D-Day Calculator
Compute D-Day from a base and target date, derive a target date from a D value, or measure the gap between two dates.
Base date
September 13, 2025
Target date → D-Day
Date difference
Target date
Select date
Include today
Exclude
Select base and target dates to compute D-Day.
All computations use the browser's local time zone.
Reset
Frequently Asked Questions
What do D+ and D- mean in D-Day calculation?
D-3 means 3 days after the base date, D+2 means 2 days before the base date.
What does 'Include Today' option mean?
How are weekdays counted?