Understanding the result
The table lists the start and end date of each period, with weekday names. Each period is inclusive: it begins at 00:00:00 on its first day and ends at 23:59:59 on its last. Use Copy to take a range as text.
What are period start and end dates?
They are the boundaries of the calendar period around a date: the Monday that starts its week, the last day of its month, the first day of its quarter, and so on. Reports, billing cycles and date filters often need exactly these boundaries.
How it works
Months and years have fixed boundaries: the first and last day of the month, or 1 January and 31 December. Quarters begin in January, April, July and October. Weeks begin on the day you choose (Monday by default, as in ISO 8601, or Sunday or Saturday) and run for seven days.
The last day of a month is calculated with the Gregorian leap year rule, so the end of February is 28 or 29 as appropriate.
Examples
Wednesday 15 May 2024
Week (Monday start): Monday 13 May to Sunday 19 May. Month: 1 May to 31 May. Quarter: 1 April to 30 June. Year: 1 January to 31 December 2024.
A date in February 2024
The month runs from 1 February to 29 February, because 2024 is a leap year.
A week that spans New Year
For 1 January 2021 (a Friday), the Monday-start week is 28 December 2020 to 3 January 2021.
Things to keep in mind
- Which day a week starts on varies by country and organisation. ISO 8601 uses Monday; the United States commonly uses Sunday.
- Fiscal years and quarters that start in other months are not modelled; the tool uses calendar periods.
- The end of a period is the last day, not the start of the next period. If your system uses exclusive end times, use the day after.