指定日までの日数カウントダウン
特定の日まであと何日か、またはあの日から何日過ぎたかを計算します。
Days until a date
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仕組みと計算ルール
- “Today” is your browser’s current local date, re-checked continuously; leave the page open past midnight and the count updates by itself.
- The count runs from today through the target date, excluding today itself: tomorrow is 1 day, matching how countdowns are read.
- A past date is reported honestly as elapsed days since, with the direction labeled instead of hidden.
知っておくと便利なポイント
- The weeks-and-days breakdown splits the same count (e.g. 100 days = 14 weeks 2 days).
- Changing your device date changes “today” on the next update, which is useful for checking a deadline against a future date.
- All counting is calendar-based, so daylight saving shifts never affect the result.
関連ツール
よくある質問
What timezone is “today” in?
Yours. The tool uses your browser’s current local date, matching how you think about “how many days left”. Changing your device date changes the answer on the next update.
Does the count include today?
No: it counts days after today through the target date, so “tomorrow” is 1 day. This matches how countdowns are read, and the rule is documented on the page.
What if the date is in the past?
The tool says so and shows the elapsed days since, rather than hiding a negative number or pretending the event is still ahead.