ISDATE returns TRUE when the expression evaluates to a date and FALSE otherwise. A date-looking text string does not automatically become a verified date merely because it looks familiar.

Syntax: =ISDATE(cell) — a single required argument, in Apple’s current English Functions Help, edition 15.4. See Apple’s ISDATE function reference (accessed 2026-10-11). There are no additional documented optional arguments or defaults for this function.

Use it to audit shipment dates, renewal dates and report cutoff dates after pasting data from a CSV or another spreadsheet. Numbers distinguishes date/time values from plain strings in its function documentation.

The important distinction is stored/evaluated value type, not the visible formatting alone. An imported value may look like a number or date while being held as text. Apple describes separate number, string, Boolean and date/time types in its value-type reference.

=ISDATE(cell)

The placeholder cell is a descriptive argument name, not text to type literally. A working reference is B6, so a complete formula is =ISDATE(B6). Write = to start a formula. The single argument has no comma of its own; nested functions with multiple arguments use commas in Apple’s English examples, or semicolons when your decimal separator is a comma according to Apple’s Functions overview. For example, =IF(ISDATE(B6),"Yes","No") becomes =IF(ISDATE(B6);"Yes";"No") in that locale.

A quick independent check

B7 contains =DATE(2024,2,29) → expected TRUE; B5 text pending → expected FALSE.

Create a table called Intake Types with a header row. Column A is a human-readable case label, column B is the value under test, and column C will contain the test formula. Create the cells deliberately—automatic input recognition can otherwise change their types.

Do not paste the B column from this Markdown table as plain text and assume Numbers will create the intended types. The date and Boolean examples are formulas, the text ID needs deliberate formatting, and B2 must remain empty. The outputs below are expected/documentation-derived, not screenshots or measurements of a live Numbers session.

Enter the formula and inspect the expected outcomes

With B7 holding the formula =DATE(2024,2,29), place =ISDATE(B7) in C7. Apple documents TRUE for an actual date and FALSE for a text value; B5 therefore returns FALSE. The displayed format of B7 may be Feb 29, 2024 or a locale-specific date, but its value type is the important part.

Documented-type expected results for =ISDATE(B2) copied through C9:

These outcomes were checked against an independent Python type-model using explicit values (blank, text, numeric, date, Boolean). That is not native Numbers execution. Automatic import/conversion and special formula-return types still require a real Numbers app validation pass.

Audit expiry dates from imported files

In a new expiry-date table, put a real date into B2 (for example using the Date & Time cell format and choosing February 29, 2024), and leave B3 as the text 2024-02-29 by setting its cell format to Text before entry. =IF(ISDATE(B2),"Valid date type","Investigate") is expected to produce Valid date type; the same formula against B3 is expected to produce Investigate under Apple’s documented type distinction. This checks type, not whether a deadline is overdue.

Avoid locale-dependent parsing

Text 03/04/2024 can be ambiguous between March 4 and April 3. Enter dates with the date picker or =DATE(2024,3,4) rather than relying on copied date-looking strings. ISDATE identifies whether Numbers already considers a value a date; it cannot infer which interpretation was originally intended.

Date and time are related, but text is not automatically date

Apple describes a date/time value as containing date and time components, even when only one component is displayed. A source CSV field is not certified as a date merely because its text resembles one. If a conversion is needed, handle it deliberately and test the result in Numbers.

• A visible date returns FALSE: check whether the cell is text imported from CSV; selecting a date display after import does not necessarily convert text.
• The date displays differently by region: verify the underlying date parts, not the textual representation.
• You expected ISNUMBER to recognize it: Apple provides ISDATE and ISNUMBERORDATE expressly for date-sensitive tests; do not assume Excel date-serial semantics.
• Value is an invalid typed date: distinguish formula/input errors from a Boolean FALSE; a date cannot be validated by formatting alone.
• native execution has not been verified: confirm date-typed entries and any date/time edge cases directly in the current Mac/iOS/iCloud version before approval.

For an initial diagnostic, try a simple function call using Apple’s examples before a complex nested expression. If a formula shows an error instead of a TRUE/FALSE result, investigate the source reference and formula syntax rather than treating the error as a Boolean FALSE. Apple has a separate error-review guide, also accessed 2026-10-11.

In the same table, use B6. Apple documents cross-table references such as Intake Types::B6 and cross-sheet references in the form Sheet 2::Intake Types::B6 when identification is needed. Selecting the cell in the Formula Editor is safer than manually guessing a qualified reference. Relative references move with copied formulas, while absolute references can be locked.

This guide follows the publicly accessible Apple Formulas and Functions Help 15.4 on 2026-10-11. The documentation also describes using the function browser in Numbers on Mac, iPhone and iPad and through iCloud.com; this does not independently establish the first Numbers app release or availability of every function on every historical platform. Native execution on Mac, iPhone/iPad and iCloud was not performed.

Google Sheets’ published function list includes ISDATE. Microsoft’s documented Excel IS-function list does not list a direct ISDATE entry, and Excel dates are commonly numeric serial values. Therefore copying ISDATE unchanged into Excel is not a safe portability assumption; devise and test an Excel-specific check.

When transferring workbooks, test the actual input types, arguments, and output on the destination software; do not assume a successful import proves formula equivalence. For help on specific cross-app function families consult Microsoft’s IS functions and Google Sheets’ published function list.

Publication note: Related guide links should be checked in the generated site. Native Numbers execution is not recorded.

• Documentation inspection: https://support.apple.com/guide/functions/isdate-ffa9cc6c78d4/15.4/web/1.0, edition 15.4, read on 2026-10-11. The syntax, argument shape and function-level TRUE/FALSE rule come from that function page.
• Cell references and locales: Apple references and Functions overview, read 2026-10-11.
• Value types: Apple value types, read 2026-10-11.
• Independent calculation: a Python type-model computed the eight tabulated expected logical outcomes and asserted the row results. This is a separate model, not an observation from the Numbers engine.
• Coverage: This function was added after the earlier eight-page Numbers launch collection.

• Apple Numbers — function documentation
• value-type reference
• Apple’s Functions overview
• Apple references

Verification status: Official documentation checked; example outcomes were independently reasoned or arithmetically checked where applicable. Not executed in Apple Numbers.

• No genuine Apple Numbers screenshots are included; this guide does not use mock application images.