Add a size chart to the product page
You can add a size chart to the Product page or the Featured product section to display page content in a popup.
For the size chart feature to work, your product must have at least one variant option. You can configure this in the Shopify admin product editor:

In the theme editor, open the Product page or Featured product section, expand the blocks list, and locate the "Variant picker" block. If it is not there, click "Add block" and select "Variant picker."

Match the variant option (for example, "Size") in the "Link from option" text field. Then select a page using the "Page content" setting to display in the popup.
In the example below, we created a page called Size chart and referenced it in the theme settings. On that page, we added an image of a size chart, but you can add any text, tables, or images using the page editor.
To quickly create HTML tables for size charts, try a responsive table generator.


Tip — Change the 'Size Chart' button text
You can change the size chart button text in Edit default theme content > Products.
Read more about changing default text.
