Date arithmetic is tested on every build against hand-worked cases, including month ends, leap days and two-digit years. How it is checked
Pick a date, or choose an occasion from the list. You get the whole days from today, with a working-day count beside it, because a deadline is usually measured in working days.
What is being counted
The figure is whole days from today to the date you named. Today is day zero and is not counted, and neither is any fraction of a day, so a date thirty days away arrives on the thirtieth day from now. This is the ordinary reading of “days until”, and with it a countdown reaches zero on the day itself.
The business-day figure removes weekends and federal holidays over the same span, which is usually the number that matters when the date is a deadline. The business days calculator counts in business days directly and lists every day it removed.
Why the count does not drift when the clocks change
A countdown built on timestamps drifts: it gains or loses an hour when the clocks change, and it can tick over at the wrong moment depending on where the reader is. This one does whole-day arithmetic on calendar dates. Local time is used only to establish what “today” is, because that depends on where you are.
The moving occasions
Most of the presets are fixed dates, and two move. Thanksgiving is tied to a weekday, so it can land anywhere in a week-long window, and the page works it out for each year. Easter moves further, anywhere from 22 March to 25 April, and has its own calculator with both reckonings and the feasts that follow from it.
Questions
How many days until Christmas?
The page opens counting down to Christmas Day, which is also in the occasion list, so the answer is above, along with the number of working days, the weeks-and-days breakdown and the weekday it falls on. It reads zero on 25 December itself, because the count is in whole days from today. If the date has already passed this year, the count runs to next year's.
Does the countdown include today?
No. Today is day zero, so a date tomorrow is one day away and a date today is zero days away. If both endpoints were counted, a countdown would read one on the day and zero the day after. The days-between calculator offers both readings if you need the other one.
Why does the business-day count differ so much from the day count?
Because roughly two days in every seven are a weekend, and federal holidays come out on top of that. Over a span of a hundred calendar days you would expect somewhere near seventy working days. If you need the exact removals, such as which day was a holiday and whether it was observed on an adjacent weekday, the business days calculator lists every one of them by name and date.
Do the occasions handle dates that move?
Yes. Two of them move. Thanksgiving is the fourth Thursday in November, so it is computed from that rule for whichever year is next. Easter moves across a thirty-five day window and is computed by the full ecclesiastical rule. The fixed occasions (New Year, Independence Day, Halloween and Christmas) are simply their dates, rolled to next year if this year's has gone.
Can I count down to a date in the past?
Yes. Enter a past date and the answer says how many days ago it was, and its wording changes to match, so it is clear which direction you are looking in.
Dates and Days