How to Add ZIP Code Restrictions in Gravity Forms

🚫 The Problem: Unwanted Submissions from Outside Service Areas

The client’s WooCommerce site was getting flooded with form entries from users outside their target ZIP code list—wasting valuable time and resources.

They wanted a simple, automatic way to stop this and only allow form submissions from approved ZIP codes.

🔍 What We Found

• Gravity Forms doesn’t support this natively. There's no built-in ZIP validation.

• A custom solution was required using a predefined ZIP list and a validation hook.

• Initially, the client wanted this for one form, but later expanded it to cover all forms site-wide.

🛠 Implementation Steps

Step 1: Create a ZIP Code List

We converted the client’s list of 209 valid ZIP codes into a PHP array:

php

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$allowed_zips = ['20105', '20109', '20110', '20111', '20112', ...];

Step 2: Add Custom Validation Hook

We used a Gravity Forms filter to check the ZIP code field before submission:

php

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add_filter('gform_field_validation_4_9', 'custom_zip_validation', 10, 4);

function custom_zip_validation($result, $value, $form, $field) {
   $allowed_zips = [...]; // your ZIP list
   if (!in_array($value, $allowed_zips)) {
       $result['is_valid'] = false;
       $result['message'] = 'Sorry, we do not service your area.';
   }
   return $result;
}

(4 = Form ID, 9 = ZIP Code Field ID)

Step 3: Resolve Other Errors

While testing, we encountered unrelated JavaScript issues that were not tied to the ZIP logic. Once confirmed, we pushed the code live without risk.

Step 4: Make It Global

Later, we upgraded the logic to work across all forms by checking for any field labeled "ZIP Code" dynamically—so no need to edit each form individually.

🚀 Results That Matter

• The site _now automatically blocks ZIP codes outside the service area.

• Lead quality and team productivity have both improved.

• The setup is easy to update or expand as needed.

💡 Want to Build Smarter Forms?

Need advanced validations, field controls, or multi-form logic? We’ll help you get the most out of Gravity Forms and your WordPress stack.

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