Checkout guard
SizeCalc doesn’t trust the price shown in the browser. Two Shopify Functions run on Shopify’s side:
- Cart transform recalculates the price of each item from its width and height, using your settings.
- Checkout validation stops the order if an item priced by size has a missing size, a size outside your limits, or a size that doesn’t fit the grid.
What customers see
Section titled “What customers see”If something is wrong, checkout shows a message such as “Please choose a size for every custom-size item in your cart.” and the order can’t be placed until it’s fixed.
Works everywhere checkout does
Section titled “Works everywhere checkout does”The functions run for the cart page, the cart drawer, Shop Pay and express checkout buttons, and on every Shopify plan.
Other apps
Section titled “Other apps”Only one app can change an item’s price with a cart transform. If another app also changes prices for the same products, use one of them for those products.