DAYNAME Function in Apple Numbers: Syntax and Worked Examples

• Introduced: Documented in Apple’s Formulas and Functions Help 15.4; the first introduction release and date remain unknown.
• Availability: Documented for Numbers in Apple’s Formulas and Functions Help 15.4; this documentation edition is not a final supported-version endpoint.
• Scope: Shared iWork reference; individual client introduction dates and older-release behavior are not established here.
• Checked: October 14, 2026, against the official DAYNAME reference. Documentation and independent calendar checks; no native Numbers test.

=DAYNAME(day-num)

The single argument is required. Apple’s reference permits a date/time value, a date string, or a number. Numeric input uses 1–7, Sunday through Saturday; a fractional part is ignored. There is no second argument for choosing a Monday-first scheme.

The distinction between a date value and a plain number matters. A value made by DATE is a date. An ordinary numeric 2 means Monday here; it is not an Excel-style date serial. Avoid feeding an imported serial number directly to DAYNAME without converting and checking the actual date.

For the examples below, use English formula names, commas and decimal points. Follow your local formula editor if it uses different separators. The names shown are English reference labels; verify the output language in the intended document before using names as exported identifiers.

Create a blank table with at least seven columns (A:G) and eight rows. Label A1 Input and B1 Weekday name. Put each entry below in the indicated A cell. A formula begins with =; the numeric entries are ordinary numbers, without quotes.

Enter =DAYNAME(A2) in B2, then fill B2 down through B8. Row 6 demonstrates truncation within the documented range: 2.9 selects day 2. It does not round to day 3.

Rows 7 and 8 are constructed from separate numeric year, month and day arguments. This avoids the ambiguity of a string such as 10/11/2026, which could be read as October 11 or November 10. Changing how a date is displayed does not change which of those two dates you originally entered.

Leave the practice table intact. In D2, enter =DATE(2026,10,14). Put these formulas in E2:G2:

The WEEKDAY default shares DAYNAME’s Sunday=1 numbering, so this round trip is consistent. In contrast, =WEEKDAY(D2,2) gives 3 under Monday=1. Passing that 3 directly to DAYNAME would produce Tuesday, because DAYNAME still uses Sunday=1. When you have the date, use DAYNAME on the date directly rather than translating between numbering systems unnecessarily.

Create a separate table named Visits, with headers Date, Visits, Day name, and Monday-first key in A1:D1. Enter:

In C2 enter =DAYNAME(A2) and fill to C4. Expected labels are Sunday, Monday, Friday. In D2 enter =WEEKDAY(A2,2) and fill to D4; expect 7, 1, 5. Sort the complete table by column D ascending when a Monday-to-Sunday report order is needed. The resulting visit sequence is 18, 25, 12.

Keep the source dates and numeric key. Alphabetically sorting the name alone creates an alphabetical list, and combining all identical names across several weeks loses the dates that distinguish those visits. The display label and the grouping rule serve different purposes.

• Wrong weekday after using WEEKDAY: check its numbering mode. DAYNAME’s numeric mapping cannot be changed.
• Unexpected result from a decimal: the documented behavior ignores the fractional part rather than rounding it. Prefer whole day codes in a data-entry sheet.
• Text date interpreted differently: use DATE with numeric components or inspect the stored date before deriving a label.
• Out-of-range code: use the documented 1–7 domain. The cited page does not enumerate exact error tokens for 0, 8, malformed text or blank references.
• Abbreviations required: DAYNAME has no documented format-string argument. Keep a separate, explicit abbreviation mapping if an export requires fixed spellings.

Do not assume a localized label is a stable machine key. Preserve the date or weekday number for joins, comparisons and sorting.