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Integration via Google Tag Manager


EyeFitU SizeEngine could be integrated into your stores via Google Tag Manager. This integration method is very versatile, it allows to customize all aspects of look and feel, functionality and integration with other tools and systems.

EyeFitU SizeEngine is added as a Custom HTML tag to Google Tag Manager which is triggered on product details page. Our tag reads product information like brand, product type and gender to give size recommendation using appropriate size guide.


Each store is unique, so we first assess your technology platform and data to outline the project roadmap. Usually project could be defined in three stages: assessment, integration and quality assurance.


EyeFitU team investigates your technology platform, data available on product pages and your size guides. This allows to define the scope and the roadmap of the integration.

We expect to receive your size guides in machine-readable form, usually it is CSV or spreadsheet document. Each size guide should list size labels and corresponding body measurement ranges which are supposed to be a fit for a given size.

Please have a look at example size guides defined for various product types: tops, bottoms, underwear and shoes.


During this stage we use your size guides to configure SizeEngine.

Based on your technology platform, EyeFitU team implements an integration tag for Google Tag Manager.

We ask for a limited Edit or Publish access permission to your Google Tag Manager container so we could do an integration. Given the Edit access to the container at Tag Manager we implement the SizeEngine™ and share it with you. We will also guide your content manager on how to configure the tag if it is not possible to grant access to the Tag Manager container.

Quality assurance

In order to confirm relevance on size recommendations we collect a set of profiles with body measurements and size expectations to confirm that size guides was applied correctly.

Technical Details

Custom HTML Tag

Content of the tag depends on your technology platform and Google Tag Manager configuration. We would take care for the implementation. Generic implementation could be seen in following code block, which we extend and adjust to your needs.

(function () {
'use strict';

var injectScript = function (url) {
var firstScript = document.getElementsByTagName('script')[0];
var script = document.createElement('script');
script.type = 'text/javascript';
script.async = true;
script.src = url;
firstScript.parentNode.insertBefore(script, firstScript);

window.eyefituConfig = {
q: [
['store', ''],
['selector', 'form .product-add-to-cart'],
['gender', 'female'],
['attributesOverride', {
brand: 'Calvin Klein',
product: 'Tanktops',


Product Details and Size Guides

EyeFitU SizeEngine reads data from product details pages to select appropriate size guide for the recommendation. It understands structured data elements placed on page, variables from data layer of Google Tag Manager and data elements of eCommerce platforms.

Giving access permission to Google Tag Manager container

  1. Sign in to your Google Tag Manager account

  2. Navigate to your GTM account, then click at 3 vertical dots on the right side

  3. Select "User Management" from the menu

  4. "Account User Management" menu will open, click "+" -> "Add users"

  5. Insert the following information:

    • Email:

    • Account Permissions: “User”

    • Container Permissions: For the relevant container select: “Edit” or “Publish”

      Note on Permissions:

    • If you select Publish, the EyeFitU team will be able to publish the sizing widget on your website. No additional setup work from you is required.

    • If you select Edit, the EyeFitU team will contact you once the integration is done and ask you to publish the sizing widget on your website.

  6. Click the "Invite" button.

You’re done! The EyeFitU team will do the rest to get the SizeEngine live on your websites!