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DAY Function (LibreOffice Calc)

Date & Time Beginner LibreOffice Calc Introduction not established

The DAY function extracts the day-of-month component (1–31) from a date or datetime value. It is essential for reporting, grouping, validation, and constructing date logic.

Verification status: Consult the documentation, examples and any stated test scope below. How formula examples are checked

Availability and version history

  • Introduced: Documented by LibreOffice 26.8.1.1; original introduction not established.
  • Availability: Supported in LibreOffice 26.8.1.1, verified against its function registry. This identifies a supported release, not a final working version.
  • Scope: Desktop Calc, using the English function name. Availability in other spreadsheet applications is separate.
  • Checked: 2026-10-14 — function reference; versioned support. Documentation/source check; not a new native test. Existing example-specific test claims below retain their stated scope.
The **DAY** function extracts the **day-of-month component (1–31)** from a date or datetime value. It is essential for reporting, grouping, filtering, constructing dates, and validating imported data. DAY works with real dates, serial numbers, and text converted with DATEVALUE.

What the DAY Function Does

  • Extracts the day of the month (1–31)
  • Accepts serial numbers, real dates, or converted text
  • Ignores year, month, and time components
  • Works with all standard date formats

It is designed to be simple, reliable, and ideal for date‑component extraction.

Syntax

DAY(date_value)

Arguments

  • date_value:
    A date, datetime, or serial number representing a date.

Basic Examples

Extract day from a date

=DAY("2024-03-15")

Returns 15.

Extract day from a datetime

=DAY("2024-03-15 08:45")

Returns 15.

Extract day from a cell

=DAY(A1)

Extract day from TODAY()

=DAY(TODAY())

Advanced Examples

Extract day from text using DATEVALUE

=DAY(DATEVALUE(A1))

Extract day from imported CSV timestamps

=DAY(DATEVALUE(LEFT(A1;10)))

Extract day from Excel serial dates imported as text

=DAY(DATE(1899;12;30)+VALUE(A1))

Determine if two dates fall on the same day-of-month

=DAY(A1)=DAY(B1)

Build a day label (e.g., “15th”)

=DAY(A1) & IF(OR(DAY(A1)=11;DAY(A1)=12;DAY(A1)=13);"th";CHOOSE(MIN(4;MOD(DAY(A1);10)+1));"st";"nd";"rd";"th"))

Extract day from YYYYMMDD text

=DAY(DATEVALUE(LEFT(A1;4) & "-" & MID(A1;5;2) & "-" & RIGHT(A1;2)))

Extract day from DDMMYYYY text

=DAY(DATEVALUE(RIGHT(A1;4) & "-" & MID(A1;3;2) & "-" & LEFT(A1;2)))

Extract day from a timestamp with timezone text

=DAY(DATEVALUE(LEFT(A1;10)))

Edge Cases and Behavior Details

DAY returns an integer (1–31)

Accepts:

  • Real dates
  • Serial numbers
  • DATEVALUE outputs
  • ISO date strings

Invalid text → Err:502

DAY ignores:

  • Time components
  • Timezones
  • Seconds/milliseconds
  • Everything after the date portion

DAY of a number < 1 → Err:502

(Serial numbers must represent valid dates)

DAY of an error → error propagates

Common Errors and Fixes

Err:502 — Invalid argument

Cause:

  • Text not recognized as a date
  • Negative serial numbers
  • Non-numeric values

Fix:

  • Wrap with DATEVALUE
  • Clean text with TRIM or SUBSTITUTE

Wrong day due to locale parsing

Fix:

  • Convert to ISO format before DATEVALUE

DAY returns unexpected value from serial numbers

Cause:

  • Serial numbers represent days since epoch

Fix:

  • Ensure imported values are converted properly

Best Practices

  • Use DAY for grouping and reporting
  • Normalize text dates with DATEVALUE
  • Use DAY with YEAR and MONTH to reconstruct dates
  • Use DAY with TODAY() for dynamic calculations
  • Use DAY with EDATE/EOMONTH for period analysis
  • Use DAY for validation of imported data
DAY completes the core date‑extraction trio — perfect for reporting, grouping, validation, and building dynamic date‑driven workflows.
  • Use YEAR and MONTH for other components
  • Use DATE to construct dates
  • Use DATEVALUE for text conversion
  • Use NOW and TODAY for dynamic values
  • Use EDATE and EOMONTH for month offsets

By mastering DAY and its companion functions, you can build powerful, reliable, and fully structured date‑analysis workflows in LibreOffice Calc.

Reproducible example (tested in LibreOffice Calc)

This standalone example was calculated in LibreOffice Calc 25.2.3.2 and matched the expected value. It is a practical cross-check of one usage, not proof that every example elsewhere on this page is correct.

=DAY(DATE(2025;1;15))

Expected result: 15.

Extract the day-of-month component from a date.

If the result differs, check the referenced cells, argument separators and number formatting. For more information, consult the LibreOffice Calc official help.