My Calculator Isn't Showing: App Embed vs App Block, and the Full Checklist

App Embed vs App Block: which does what, and why you need both

Custom Price Calculator has two separate switches in your Shopify theme. Turning on only one is the single most common cause of “my calculator isn’t showing”.

• The App Embed loads the CPC script across your storefront. It renders nothing visible — it switches the power on.
• The App Block is what you place on your product template in the theme editor. It renders the calculator and controls where it sits.

The embed alone is not enough: the script loads, calculates nothing, shows nothing.

The 60-second check

In order. Most cases are fixed by step 2 or step 5.

1. App Embed is on. On your live theme: Online Store → Themes → Customize → App embeds, turn Custom Price Calculator ON, Save.
2. App Block is on the product template. Still in Customize, open a product page, click Add block, choose Custom Price Calculator under Apps, drag it into position, Save.
3. The product is assigned to the calculator — in the app, open the calculator, Products tab, tick the product, save. See Adding a calculator to Product Pages.
4. The theme’s native Add to Cart block is still there. The calculator mounts onto Shopify’s native product form (form[action="/cart/add"]). Delete the Buy buttons block and there is nothing to attach to, so nothing renders even with the embed and block in place. Add Buy buttons back and save.
5. Check the live product page, not a preview. Open the real product URL and hard-refresh (Ctrl + Shift + R, or Cmd + Shift + R on Mac), or use an incognito window.

It never renders in the theme editor or a preview

Normal, not a fault. In Customize, in the app’s own preview and on theme preview links you see only a placeholder block. The calculator builds itself only on a live, publicly loaded product page.

Only the embed carries over between themes

The embed setting generally follows you when you switch or publish a theme. The block does not: it lives in one theme’s product template, so a newly published, duplicated or freshly installed theme has none. “The calculator broke after I published a new theme” is nearly always just that; your calculators and data are untouched. Set every theme up fully before a switch or A/B test — one merchant lost roughly six weeks of testing to a second theme that never had the block.

On a backup, duplicate or unpublished theme the calculator may load but show NaN or 0, because the embed registers per theme. Toggle that theme’s embed off, then on, and Save.

“Failed to render app block… does not exist”

The calculator vanishes overnight, you changed nothing, and the page source may show that message. After an app update the block saved in your theme can still point at an older version of the extension, so Shopify silently refuses to render it. It looks like the app deleting itself; it isn’t, and your calculators and product assignments are untouched.

Fix: in Customize → App embeds, toggle Custom Price Calculator off then on, Save, re-check the live page. Still missing? Remove the old CPC block from the product template, add it again, save.

Old calculator.js script tags must be removed

Legacy setup meant pasting a <script> tag for calculator.js into theme.liquid. If one is still there the calculator loads twice and the copies conflict — usually a price that won’t update. In Online Store → Themes, open the … menu, choose Edit code, open layout/theme.liquid, search calculator.js, and delete that <script> line plus any old CPC snippet pulled in with {% include %} or {% render %}. Do this in every theme, duplicates included. Never add a script tag to fix a display problem — that approach is retired and now causes faults. If it still loads twice, contact support rather than editing further.

Three more limits

• Page builders. On a PageFly or Instant product page the native product form is often missing, so the calculator can’t mount — use your theme’s native product template. For non-product landing or quote pages, use the Non-products feature: Adding a Calculator to a Non-Product Page.
• The embed can’t be scoped to certain products for page speed. It loads site-wide, as Shopify’s app embed system requires; narrowing it needs unsupported custom theme development. Scoping it to product pages is a logged feature request.
• Which products show a calculator is set in the app, not the theme. A calculator appears only on products you assign it to, so to hide one, don’t turn the embed off — that breaks every other calculator on the store. Unassign the product, or archive the calculator.

Still nothing? Two more checks

Test for a theme or app conflict. Temporarily switch to Shopify’s Dawn theme and open the product page. If the calculator appears in Dawn but not in your own theme, the cause is a conflict in that theme or with another app, not the calculator setup.

Check where it is set to appear. Open the calculator in the app, go to Settings and review the Calculator Placement setting. If you are not sure which option you need, choose the default placement and save.

Still not showing?

Start a chat from the app and include four things, which is usually enough for us to diagnose it without a back-and-forth: the live product page URL, your theme name, whether that theme is published or a duplicate or a backup, and a screenshot of the product template showing the CPC block.