Countdown calculator
A countdown is the gap between today and a future date. The first field defaults to today, so entering the target date is all it takes. Days, weeks, months and the calendar breakdown are all shown at once.
How to count down to a date
Countdowns almost always want exclusive counting; days remaining, not days occupied. "Three days until Friday" said on a Tuesday means Wednesday, Thursday, Friday are still to come in one reading and only Wednesday and Thursday in another. This tool defaults to the gap, which is the more common reading for a countdown, and offers the inclusive count for anything being occupied rather than awaited.
Questions
Enter the date: today is filled in for you and the gap is shown.
For a countdown, usually not. Switch to inclusive counting if it should.
Yes. It becomes a count up, and the direction row says so.
It uses today as of when the page loaded. Reload for a new day.
This works in whole days. For hours and minutes you need a datetime countdown.