How to implement captcha in Google Form? How to validate data entered in Google Forms? How to make sure that Google Form will be filled out with answers according to the given directions? These are the most asked questions when it comes to design and implementation of any questionnaire, including the Google Forms.

Depending on the type of the question, there are several types of validation tools available as part of the Google’s form designer.

If the question type is “Text” then you have Number, Text or Regular Expression as validation tools (only one at a time).

When the question type is “Checkboxes” then you have different validation tools: Select at least, Select at most and Select exactly.

We will see what each one of these validation methods means through different examples.

1. Validate email address

If you require from the respondents to enter their email address then the Question type should be “Text”. Then, enable the Data validation and choose these options respectively: Text > Email address. Type some custom error text.

validate email address in google form

Notice: According to some comments I found in the Internet forums, this might not be the perfect solution. However Google can identify and recognize the most common email domains.

2. Implement CAPTCHA

In order to make sure that your form is being filled by a human and not a computer robot, it is highly recommended to ask your respondents some logical question. I usually place this question right before my respondents hit the Submit button.

For “Question type” choose “Text”, enable Data Validation, then in the first combo box choose Text, in the second choose “Not between” and finally any numbers of your choice. Mark this question as required.

Google Form Captcha

3. Ensure the exact number of answered questions

This feature will probably be utilized mostly by academic institutions. This validation mechanism ensures that student will mark the exact number of answers as it is required by the teacher. It doesn’t mean they are correct, of course.

Question type is Checkboxes. After enabling Data validation, choose “Select exactly” option and put number 3 in the next field. Provide custom error text.

Validate checkbox answers

4. Regular expressions as validation tool

If you are an advanced user you can consider to create custom regular expressions. According to a definition on the Google’s Support site:

“Regular expressions provide a way to identify certain types of text, including particular characters, numbers, words, or patterns of characters. Regular expressions are particularly useful in pattern matching, as these searches are not restricted to a specific search term. Instead, searches return patterns that match the expression specified.”

Let’s see some examples of form validation by using regular expressions.

Validate email address – Check if email address is from any of these domains:,,

  • (\W|^)[\w.+\-]{0,25}@(gmail|mail|live)\.com(\W|$)

Limit the number of characters – the Paragraph text box, basically doesn’t impose certain limit on entered text, but if you want you can define maximum number of characters in specific text box. This regular expression (or shortly RegEx) ensures that answer can contain between 1 and 800 characters:

  • [\w]{1,800}


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