The ISDATE function in Google Sheets verifies whether a cell contains a valid date or if all values in a range are dates. This function is simple yet crucial for data validation and manipulation.

Understanding How Dates Work in Google Sheets

In Google Sheets, dates are stored as serial numbers. For example, when you apply Format > Number > Date to a cell containing 0, it displays 30/12/1899, and 1 displays 31/12/1899.

However, if you test a number using ISDATE, it will return FALSE. This means the function accurately identifies proper dates and differentiates them from numbers.

The ISDATE function in Google Sheets also helps verify whether a date is entered in the correct format. For instance, if a date is mistakenly entered as MM/DD/YYYY when the expected format is DD/MM/YYYY, ISDATE will return FALSE.

Syntax and Usage of the ISDATE Function in Google Sheets

Syntax

ISDATE(value)

Where value is usually a cell reference that you want to evaluate.

Examples

1. Checking a Single Cell

=ISDATE(A1)

This formula returns TRUE if A1 contains a valid date. Even if you apply Format > Number > Plain Text to a valid date cell, ISDATE will still return TRUE.

2. Checking a Range

=ISDATE(A2:A9)

This checks whether all values in the range A2:A9 are valid dates. If there are numbers, empty cells, or text in between, it will return FALSE.

3. Checking Each Row Individually

If =ISDATE(A2:A9) returns FALSE, it means at least one non-date value exists in the range. To find which rows contain non-dates, use MAP:

=MAP(A2:A9, LAMBDA(dt, ISDATE(dt)))

The MAP function applies the LAMBDA function to each value in the array, returning TRUE or FALSE. Here, dt is a variable representing the current element in the array.

This approach helps clean up data, but LAMBDA functions can be resource-intensive in large datasets, potentially affecting sheet performance.

ISDATE vs. DATEVALUE: Key Differences

DATEVALUE: A Better Alternative to the ISDATE Function in Google Sheets

The DATEVALUE function extracts a serial number (date value) from a date string or a valid date. It accepts multiple input formats, but it does not recognize fully written date formats like:

Thursday, 13 February 2025 at 00:00:00

Using DATEVALUE as an Alternative to ISDATE

To use DATEVALUE as an alternative to ISDATE, ensure the date range is formatted properly:

1. Select the date range.
2. Apply Format > Number > Date to ensure a clean date format.

Then, use this formula:

=ArrayFormula(ISNUMBER(DATEVALUE(A2:A9)))

This approach avoids using LAMBDA, making it more efficient for large datasets.

Common Errors and Fixes

Issue: ISDATE returns FALSE for dates formatted as date values.

Fix: Apply Format > Number > Date before checking.

Issue: DATEVALUE does not recognize certain date formats.

Fix: Ensure the input string follows a standard format such as DD/MM/YYYY or YYYY-MM-DD.

FAQ

How can I check if a cell is a date in Google Sheets?

Use:

=ISDATE(A1)

Can ISDATE validate dates entered in different formats?

No, ISDATE only checks if a value is stored as a date, not if it follows a specific format.

How do I convert text dates into actual dates in Google Sheets?

Use:

=DATEVALUE(A1)

Ensure the cell format is set to Date.

Resources

• Google Sheets: The Complete Guide to All Date Functions
• How to Use the TO_DATE Function in Google Sheets
• Convert Text Dates with Dots to Slash Format in Google Sheets
• How to Use Date Criteria in the FILTER Function in Google Sheets
• How to Use Date Criteria in QUERY Function in Google Sheets
• REGEXMATCH Dates in Google Sheets – Single/Multiple Match
• Finding the Closest Date to Today in Google Sheets
• Extracting Date From Timestamp in Google Sheets: 5 Methods
• How to Convert Date to Month and Year in Google Sheets