DAY Function in Collabora Office Calc: Formula, Examples & Troubleshooting

=DAY(serial_number)

A valid date serial or date expression. In formula syntax, square brackets mark optional arguments; do not type square brackets into an ordinary formula unless the particular function requires array notation. The separator shown is for the example locale and might change with spreadsheet settings.

When to use it: DATE and EOMONTH help create unambiguous monthly boundaries.

Use a fresh Collabora Calc document with English function names. The sample formulas below use semicolons, consistent with the Calc-style reference default. Ensure the number cells are stored as numeric values. These two examples use literal values, so you can enter them into blank cells without first constructing a table. Their answers are independent calculations; dates must be displayed with an actual date format.

=DAY(DATE(2026;10;11))

Expected result: 11. The day component of October 11 is 11.

1. Select an unused output cell (for example H2 if the practice table occupies A1:F9).
2. Enter the formula exactly as shown, including the opening equals sign and quoted text.
3. Compare the displayed answer to the expected result, then inspect the source cells if it differs.

For a range formula, the row numbers include data rows only unless the example explicitly refers to headers. A result that looks plausible may still be wrong if it references the wrong column.

=DAY(DATE(2024;2;29))

Expected result: 29. Leap-day date returns day 29.

Enter the second check in an unused cell, keeping its source inputs untouched. The result should follow from the stated values even before testing a different workbook.

Watch out: DAY is day-of-month, not day-of-week; use WEEKDAY for weekday numbers.

Collabora deployment and release matters, especially for newly added functions. Named-function and formula-reference settings can change parsing without changing the intended mathematics.

If Collabora displays a formula error, confirm the argument delimiter is a semicolon, the selected language for function names and the cell reference syntax setting. Calc-style wildcard/regular-expression matching can be controlled by formula options and should not be assumed to match Excel defaults.

If you get the wrong answer but no error, try these checks in order: (1) evaluate the simplified first example; (2) confirm the cell values and data types; (3) check the exact row and column boundaries; (4) verify quoted text, comparison operators and separators; (5) only then add more criteria or nested functions.

For a reproducible comparison with another spreadsheet product, use the same input values in both applications and record the installed version and locale. Different default matching behavior or handling of empty values can be a migration issue rather than a mathematical disagreement.

Collabora Calc normally uses Calc-style semicolons and supports selectable Calc A1, Excel A1 and Excel R1C1 reference styles. Microsoft Excel English examples usually use commas and use Sheet2!A1 rather than Calc’s Sheet2.A1.

Related guides already published for this function: Microsoft Excel | Google Sheets | WPS Spreadsheet | LibreOffice Calc | Apache OpenOffice Calc

If a comparison tool says Not researched here, that means we do not yet have a checked guide for that software. It does not mean the software lacks this function. See the 12-program comparison tool for a guide-coverage matrix.

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Evidence level: Vendor-published function catalogue / formula overview, checked for this editorial batch on October 11, 2026; example outputs verified by direct reasoning/arithmetic where applicable. No execution in Collabora Office Calc was performed. Some platform-, language- and release-specific edge cases remain for native testing.