Size Chart Popups: Themes That Ship Them vs 10-Dollar Apps

Most merchants typing “shopify size chart popup” into search assume they need to install something, because the word popup suggests a separate widget bolted onto the product page. That assumption skips a step. Seven themes published by UTD in the official Shopify Theme Store already carry a size guide setting as part of the product template itself, not as an add-on, and it is turned on by default in every one of them. The real question is not whether the theme has it, it is what that one checkbox can and cannot do once it is switched on.

The setting exists in every UTD theme checked, under the same name

Across Allure 1.2.5, Boutique 2.3.4, the Fuse archive dated 2026-09-07, Gain 4.3.1, Impression 1.1.1, Ultra 2.3.4 and Victory 1.2.2, the setting is show_size_guide, a checkbox labeled “Show size guide,” and it lives in the same file every time: sections/featured-product.liquid. All seven ship it enabled by default. That consistency across seven separate theme codebases, built and versioned independently, means a merchant switching between any of these seven does not lose the setting, they just find it sitting among a different number of neighbors.

The counts rest on a direct read of each theme’s own schema file in sections/featured-product.liquid, across all seven themes published by UTD in the Shopify Theme Store, checked October 15, 2026.

What the checkbox actually controls, and what it leaves to the merchant

The facts describe show_size_guide as a single boolean. It turns the size guide link or block on or off on the product page. None of the seven themes’ measured settings describe a separate chart-builder interface, a table editor, or a per-product-type switch living next to this checkbox. That means the actual sizing content, the inches, centimeters, or garment measurements a shopper reads, is something the merchant has to build separately, typically through a page or a metafield referenced elsewhere in the template, not something the checkbox generates on its own. A ten-dollar app that promises per-product size charts is solving a content and data problem, not a visibility problem, and the visibility problem is already solved in the theme.

The setting is not just in the code, it renders on live demo storefronts

Beyond the schema files, the size_guide or size-guide marker was found actually present on rendered pages during an October 15, 2026 pass across six public demo stores. Allure’s demo at demo-store-mini-pollheim-suits.myshopify.com shows it on the homepage, collection, and product pages. Boutique’s demo at demo-the-lace-boutique.myshopify.com shows it on the same three page types. Ultra’s demo at demo-store-ultra-electronic.myshopify.com and Victory’s demo at demo-bobabam.myshopify.com show it specifically on product pages, and Impression’s demo at gallery-theme-demo-3.myshopify.com and Gain’s demo at gain-demo2-store.myshopify.com show the same marker on product pages too. Six independently hosted storefronts, each running a different theme, all surfacing the identical marker, is a stronger signal than a schema entry alone because it confirms the setting is wired all the way through to the customer-facing template.

The setting sits inside a crowded panel, and that crowding varies by theme

The size guide checkbox does not live alone. In Gain 4.3.1 and Boutique 2.3.4 it shares its settings area with 14 total entries, the most of the seven. In Impression 1.1.1 it shares the area with only 10, the fewest. That gap of four settings does not change whether the size guide works, but it does change how much scrolling and configuration a merchant faces inside that one panel of the Shopify editor, which is a real cost even when every underlying feature is free. A theme store listing does not surface that difference, and neither does a feature checklist that just says “size chart: yes” for every entry, which is exactly the kind of flattening that sends people looking for a paid app to solve a problem their theme already solves.

Check the specific theme version in use against sections/featured-product.liquid before buying an app, and treat the show_size_guide checkbox as the starting point, not the finish line, since it only toggles visibility and leaves the actual chart content for the merchant to supply.