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How to display a Quantity Selector for each cart item on the Checkout using the Template/Custom -> Cart Item Details -> Line item editor option.

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Guide

1

Create a new customization

Create a new customization.Image
2

Select the Cart Item Details category

Choose Line Item Editor as the customization from available types of Cart Item Detail.Custom Cart Item Details Card Focus
3

Configure display conditions

Add one or more conditions to control when the quantity selector is displayed during checkout.Line Item Conditional Experience Focus
4

Configure Line Item Actions

Click on Quantity Stepper checkbox to configure relevant action.Line Item Actions Focus
5

Set the priority

Configure the Priority (0–100) to determine the execution order when multiple customizations are eligible.Line Item Priority Focus
6

Activate the customization

Change the Status to Active using toggle button to enable the customization.Line Item Toolbar Focus
7

Copy the Placement ID

Copy the generated Placement ID from clipboard icon. You’ll use this in the Shopify Checkout Editor.Line Item Copy Placement Id Focus
8

Preview

Preview shows , How this block looks like at CheckOut.Line Item Editor Preview Focus
9

Save the customization

Click Save to store your configuration.Line Item Unsaved Changes Focus
10

Open the Checkout Editor

Go to your Shopify Settings → Checkout, select your checkout profile, and click Edit.
11

Add the app block

In the Checkout Editor, click Add app block.Screenshot 2026 10 08 At 16 32 10
Make sure the app block is placed in the same checkout placement you selected in Dynamic Checkout Customizer.
12

Configure the app block

Select the Checkout – Edit cart item app block, and paste the copied Placement ID.Screenshot 2026 10 08 At 16 32 42
13

Publish your changes

Click Save in the Checkout Editor to publish the customization.Swap Clean
Why does it matter?The Cart Item Details → Adjust Quantity customization lets customers update product quantities directly during checkout, reducing friction and making it easier to increase order quantities without returning to the cart. This can help improve average order value (AOV).