The Dates
04 WaysResult
LiveHow Days Are Counted
How it worksDisagreements come from the first day, not the arithmetic.
D-day excludes today
If the exam is tomorrow it is D-1, not D-2. The gap is counted, so today itself is not one of the remaining days.
Today → tomorrow = D-1
Anniversaries include the first day
The Korean convention counts the starting day as day one, so the day you met is 1일, not 0일. That is why an anniversary sits one higher than the gap.
Start day = 1일 · gap + 1
Leap years are handled
February 29 is counted whenever the range crosses it. You never have to adjust for it by hand.
2024-02-01 → 2024-03-01 = 29
Time of day is ignored
Everything is measured in whole calendar days in your own time zone, so the number never shifts as the clock moves.
Calendar days · local time
Questions
03Why is my D-day one off from another site?
Some sites count today as a remaining day. This tool counts the gap, so tomorrow is D-1.
Does it handle dates before today?
Yes. A past target simply returns a D+ number instead of D-.
What time zone is used?
Your device’s own time zone. Nothing is sent to a server, so there is no clock to disagree with.