How to Add a Size Guide Popup to Shopify

Why Use a Size Guide Popup

A size guide popup shows your measurements in a modal when the shopper clicks a "Size guide" link — keeping the chart accessible without pushing your product details down the page. It's a clean pattern, and it's far better than a separate page the shopper has to navigate away to.

But a popup is still a chart in a box. It's a good baseline; just know its limits before you assume it will fix returns.

Step-by-Step: Adding the Popup

On an Online Store 2.0 theme, the easiest route is an app or app block:

1. Install a size guide / size chart app from the App Store.
2. Go to Online Store → Themes → Customize.
3. On the product template, add the app's block (or enable its app embed).
4. Position the Size guide trigger next to the size selector.
5. Configure the chart content per product or per category.
6. Save and preview.

If you prefer a manual approach, you can add a link that opens a modal containing a chart, but an app keeps it maintainable across theme updates.

Placement and Mobile

• Trigger placement: put the "Size guide" link right beside the size selector — that's where the doubt happens.
• Mobile: make sure the modal is scrollable, readable, and easy to dismiss on small screens, where most fashion traffic lives.
• Don't auto-open aggressively: a popup that fires unprompted on every page load annoys more than it helps.

The Limit of a Popup Chart

A popup makes your size chart convenient, but it doesn't change what a chart is: information the shopper still has to interpret. It answers "what are the measurements?" not "which size fits me?" As we explain in Size Chart vs Size Recommendation, that interpretation gap is exactly where bracketing and returns come from.

If you've added a polished size guide popup and still see high size-related returns, the popup isn't the problem — the chart-only approach is.

When to Upgrade to a Recommendation

Move from a popup chart to a size *recommendation* when:

• Returns stay high despite a clear, accessible chart.
• Shoppers bracket (order multiple sizes).
• You sell categories where measurements alone don't predict fit.

For the broader merchant playbook, see How to Lower Your Shopify Return Rate.

Where YourSizer Fits

You can keep your size guide popup for reference and add YourSizer for the decision — a product-specific recommendation that tells each shopper their size instead of leaving them to read a chart. See it for brands, shoppers, or pricing.

Sources

• Size guide conversion impact
• Size guide UX research

Frequently Asked Questions

How do I add a size guide popup to Shopify?

Install a size chart app on an Online Store 2.0 theme, add its block or app embed in the theme editor, and place the "Size guide" trigger next to the size selector so it opens in a modal. No custom code is required.

Does a size guide popup reduce returns?

It helps by making sizing convenient, but a popup is still a chart the shopper must interpret. To meaningfully reduce returns, pair it with — or upgrade to — a size recommendation that gives a confident, product-specific answer.

Should a size guide popup open automatically?

Generally no. An aggressive auto-open on every page load tends to annoy shoppers. Trigger it on click, placed next to the size selector where shoppers actually look for help.