Project planning
Measure how many working days sit between kickoff and launch.
単位変換
日付期間計算ツール
任意の2つの日付間の時間を秒単位で測定します。
開始日と終了日を選択すると、期間の長さが日数、週数、月数、年数、および一般的な営業日単位で即座に表示されます。
Calendar-day difference
Date after or before N days
Weekdays only vs business days with holidays
Count days between dates
Pick a start and end date to measure the calendar span. Results use standard “between dates” semantics, so the same day returns 0 days.
Quick planning presets
Set the end date from the start date with one tap for common planning horizons.
Days between your dates
There are 30 calendar days between 2026年2月28日 and 2026年3月30日.
Months and years are approximate so you can estimate longer timelines quickly.
Calendar days
30
Weekdays only (Mon–Fri)
21
Counts weekdays after the start date up to the end date.
Selected workweek days
21
Mon-Fri
Business days with holidays
21
Starts from the weekday count, then removes national public holidays for the selected country.
Weeks (exact)
4.29
Months (approx.)
0.99
Years (approx.)
0.082
Excluded holidays
No holiday dates were excluded for the current range and workweek.
Add or subtract days from a date
Find the date after 7, 30, or 90 days, or move backward from a deadline to a planning start date.
Offset shortcuts
Use positive values for future dates and negative values for past dates.
+30 days from 2026年3月30日 is 2026年4月29日.
Resulting date
2026年4月29日
Day of week
水曜日
Weekdays and business days
Compare the raw weekday count with a holiday-aware business-day count so you can plan staffing, approvals, shipping, and project schedules more accurately.
The holiday-aware count uses public holidays for the selected scope.
Optional. Use a more specific holiday scope when your planning depends on state-level public holidays.
Custom workweek
Pick the weekly schedule that matches your team, operation, or market before holidays are removed.
United States
Public holidays can be filtered by the selected holiday scope. Company shutdowns and custom leave calendars are not included.
2026
When this date calculator helps most
Shipping and procurement
Check whether a quoted lead time includes weekends or public holidays.
HR and operations
Count business days across notice periods, onboarding windows, or approval timelines.
よくある質問
うるう年は考慮されますか？
はい。この計算ツールは実際の暦日を数えるため、うるう日や月の長さは自動的に含まれます。
営業日はどのように計算されますか？
営業日の合計には月曜日から金曜日までが含まれ、土曜日と日曜日は除外されます。祝日は除外されません。
過去にさかのぼって測定できますか？
もちろんです。終了日が開始日より早い場合、ツールは自動的に日付を入れ替え、正の期間を返します。