D-Day Calculator
Count the days to or since any date, see the gap in weeks and months, list milestones like 100 days and anniversaries, and save or share your countdowns.
Milestones
Saved dates stay in this browser only and are never sent to a server. Up to 12 can be saved.
How to use the D-Day Calculator
- Pick a date. The count appears straight away, with nothing to press.
- A future date shows D- and the time left in weeks and months; a past date shows D+ and the time since.
- For anniversaries counted from a past date, tick Count the start date as day 1.
- The table lists milestones such as 100 days and anniversaries, or checkpoints such as D-30 and D-7. Save the date on this device or send it as a link.
Reading D-1, D-Day and D+1
D with a minus is the number of days still to wait, so D-10 means your date arrives ten days from today and D-1 is the day before it. The date itself is D-Day rather than D-0, and later days count upward as D+1, D+2 and so on.
| The date is | Shown as |
|---|---|
| 30 days from today | D-30 |
| tomorrow | D-1 |
| today | D-Day |
| yesterday | D+1 |
| 100 days ago | D+100 |
Both ends are read at local midnight
The target is built from its year, month and day in your device's own time zone, and today is set back to 00:00 before subtracting. Reading it as UTC instead would put anyone in a zone behind UTC a day out.
Frequently asked questions
How is the target day shown?
The day itself appears as D-Day.
Can I count backwards from a past date?
Yes. Dates that have already passed are shown as D-plus the number of days elapsed.
Is today counted in the number?
No. The figure is how long you wait, so D-10 means ten more days. Add one for a total that includes today and the target day.
Can I count from a date other than today?
The count always runs from today. For the gap between two dates of your choice, use the date difference calculator. For anniversaries, enter the start date and the table lists 100 days, 1,000 days and each year.
What does D+30 mean?
Thirty days have gone by since the date you entered. Past dates count upward like this, which is how anniversaries are tracked.
When is my 100-day anniversary?
Enter the start date and tick Count the start date as day 1, the usual way couples count. The 100-day mark is then 99 days after the start, and the table lists later milestones too.
Can I save several countdowns?
Save on this device keeps up to 12 dates in this browser, shown at the top next time with their D-number. Nothing is sent to a server; to share one, copy its link.