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 embed alone is not enough: the script loads, calculates nothing, shows nothing.
In order. Most cases are fixed by step 2 or step 5.
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.Ctrl + Shift + R, or Cmd + Shift + R on Mac), or use an incognito window.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.
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On a backup, duplicate or unpublished theme the calculator may load but show NaN or 0, because the embed registers per theme.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.
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.
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.
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.
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.