Add the Block to Your Theme

Size charts appear on your storefront through a theme app block. You add it once to your product template — every chart you assign afterwards shows up automatically, with no further theme changes.

This is the step most merchants miss. Until the block is added, charts stay invisible on your store — even when they’re assigned and live. The app warns you on Home when this happens.

Step 1: Open the theme editor

From the app Home page, use the Open theme editor button in the setup guide, or
In Shopify admin, go to Online Store → Themes → Customize on your live theme.

Step 2: Add the Size chart block

At the top of the theme editor, open the page selector and choose Products → Default product (or the specific template your products use).
In the left sidebar, click Add block (or the + in the section area).
Find Size chart under Apps and click it.

The block has no settings to configure — all configuration lives in the app.

Step 3: Save and verify

Click Save in the theme editor.
Open a product that has a chart assigned. You should see the Size guide link (by default next to the size label, or under the size options).

Where the link appears

You control the trigger position on the app’s Appearance page:

Next to size label (default) — on the same line as “Size”; falls back to an inline link.
Inline link — under the size options.
Floating button — corner of the page.
Expandable row — opens in place.

See Appearance and the master template.

Published a new theme?

The app block is installed per theme. When you publish a new theme, add the block again — the app detects this and shows a banner on Home with a direct link into the theme editor. See Troubleshooting.

Canvas themes

Themes built on Canvas don’t support app blocks, so the widget can’t be installed on them. The app detects this and shows a banner explaining the limitation.