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第26週
ISO週番号
月 6月 22 – 日 6月 28, 2026
| Week # | 月 (Start) | 日 (End) | 対象月 | 四半期 | 日 |
|---|
よくある質問
What week number is it today?
今日は Week -- of 2026. ISO週 start on 月曜日 and end on 日曜日.
How are ISO week numbers calculated?
ISO 8601 defines a week as starting on 月曜日. Week 1 of a year is the week that contains the first 木曜日 of the year (or equivalently, the week containing 1月 4th). This means 1月 1 can sometimes be in the last week of the previous year (Week 52 or 53).
How many weeks are in 2026?
2026 has 52 ISO週. The year starts on 木曜日, 1月 1, and ends on 木曜日, 12月 31. Week 1 of 2026 begins on 月曜日, 12月 29, 2025.
What is the difference between ISO week and calendar week?
ISO週 (ISO 8601) always start on 月曜日. In the US, calendar weeks often start on 日曜日. This means an ISO week number may differ from a US-style week number by 1 depending on the day. OnlineCalendar.org uses ISO 8601 week numbering.
When does Week 1 of 2027 start?
ISO Week 1 of 2027 starts on 月曜日, 1月 4, 2027 — because 1月 1, 2027 falls on a 金曜日, and Week 53 of 2026 covers 12月 28, 2026 – 1月 3, 2027.