時間ツール
カウントダウン計算機
新年、誕生日、試験など、任意の日時までのカウントダウンを作成します。
ほとんどのツールはブラウザ内でローカル処理します。背景除去では選択した画像を設定済みサーバーで処理し、完了後に元画像を削除します。
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使い方
- Choose New Year, Christmas, Halley's Comet return or Custom Event.
- For a custom event, enter a name, date, time and IANA time zone, then choose the display precision.
- Select Start Countdown. Copy, share, add the event to your calendar or open a focused fullscreen view.
おすすめの用途
- Birthdays, trips and launches
- Exam and project planning
- Events across different time zones
注意点
A browser countdown updates while this page is open; a closed page cannot provide reliable notifications. Confirm important dates with the relevant official source.
よくある質問
How do I create a custom countdown?
Choose Custom Event, enter a valid future date and time, select an IANA time zone and press Start Countdown.
Will the countdown keep running after I close the page?
No. It recalculates when the page is open or becomes visible again. A closed browser tab cannot reliably run a reminder.
Can I share a countdown?
Yes. Share creates a URL containing only the validated event name, date, time, time zone and display precision.
How do I add a countdown to my calendar?
Use Add to Calendar to download a local .ics file. Nothing is uploaded.
Does the countdown support different time zones?
Yes. Enter an IANA zone such as Asia/Shanghai, America/New_York or Europe/London. The browser applies the correct offset and daylight saving rules.
Is my event information uploaded to a server?
No. Calculations, URL creation and calendar generation happen locally. Event values are not sent to analytics.