How to Use the ISURL Function in Google Sheets to Validate Web Links

The Problem with Messy Data Entry

If you manage a marketing team, run an affiliate link program, or collect customer data via Google Forms, you frequently deal with spreadsheets full of website addresses. A common problem is human error: users type “google.com” instead of “https://google.com”, or they accidentally include spaces, typos, or completely invalid formatting.

When this data is exported to another software platform (like an email marketing tool or a CRM), those improperly formatted links will break, causing failed redirects and poor user experiences.

To prevent this, you can use Google Sheets’ incredibly simple, yet highly effective ISURL function. This function instantly validates whether a string of text is a properly formatted, clickable web address.

Understanding the Syntax

The syntax for ISURL requires only one argument:

=ISURL(value)

• value: This is the cell reference (e.g., A2) or the hard-coded text you want to evaluate.

The function returns a boolean output: TRUE if the text is a valid URL, and FALSE if it is not.

Example 1: Basic Validation

Assume you have a list of user-submitted website addresses in Column A, starting at A2. You want to quickly identify which ones are broken.

In cell B2, type:

=ISURL(A2)

Drag the formula down the column. Google Sheets uses a strict validation protocol. For example:

• https://www.digitash.com will return TRUE.
• http://digitash.com will return TRUE.
• www.digitash.com will return FALSE (because it lacks the required http/https protocol prefix).
• digitash .com will return FALSE (because URLs cannot contain spaces).

Example 2: Combining ISURL with Conditional Formatting

While having a column of TRUE/FALSE values is helpful, it is much more visually effective to highlight the broken links in red so they stand out immediately.

1. Highlight your entire column of URLs (e.g., Column A).
2. In the top menu, click Format > Conditional formatting.
3. In the sidebar, under the “Format rules” drop-down menu, select Custom formula is.
4. Enter the following formula, which tells Google Sheets to flag the cell if ISURL returns FALSE:
   =ISURL(A1)=FALSE
   (Ensure you use A1, or the very first cell in your highlighted range, so the formatting applies correctly down the column).
5. Under “Formatting style,” change the fill color to red.
6. Click Done.

Now, anytime a user pastes a broken link into the sheet, the cell will instantly turn bright red.

Example 3: Using ISURL for Data Validation

If you want to physically block users from typing a bad URL into your spreadsheet in the first place, you can embed the ISURL function into a Data Validation rule.

1. Highlight the column where URLs will be entered (e.g., A2:A100).
2. Go to Data > Data validation.
3. Click Add rule.
4. Change the Criteria drop-down to Custom formula is.
5. Enter the formula: =ISURL(A2)
6. In the Advanced options, choose Reject the input and add a custom warning message like: “Please include the full https:// prefix.”

By enforcing this rule, you guarantee that every single link in your database is structurally sound before it ever reaches your CRM or marketing software.