---
title: cartLinesUpdate - Storefront API
description: >
  Updates one or more merchandise lines on a
  [`Cart`](/docs/api/storefront/2025-07/objects/Cart). You can modify the
  quantity, swap the merchandise, change custom attributes, or update the
  selling plan for each line. You can update a maximum of 250 lines per request.


  Omitting the
  [`attributes`](/docs/api/storefront/2025-07/mutations/cartLinesUpdate#arguments-lines.fields.attributes)
  field or setting it to null preserves existing line attributes. Pass an empty
  array to clear all attributes from a line.
api_version: 2025-07
api_name: storefront
type: mutation
api_type: graphql
source_url:
  html: 'https://shopify.dev/docs/api/storefront/2025-07/mutations/cartLinesUpdate'
  md: 'https://shopify.dev/docs/api/storefront/2025-07/mutations/cartLinesUpdate.md'
---

# cart​Lines​Update

mutation

Updates one or more merchandise lines on a [`Cart`](https://shopify.dev/docs/api/storefront/2025-07/objects/Cart). You can modify the quantity, swap the merchandise, change custom attributes, or update the selling plan for each line. You can update a maximum of 250 lines per request.

Omitting the [`attributes`](https://shopify.dev/docs/api/storefront/2025-07/mutations/cartLinesUpdate#arguments-lines.fields.attributes) field or setting it to null preserves existing line attributes. Pass an empty array to clear all attributes from a line.

## Arguments

* cart​Id

  [ID!](https://shopify.dev/docs/api/storefront/2025-07/scalars/ID)

  required

  The ID of the cart.

* lines

  [\[Cart​Line​Update​Input!\]!](https://shopify.dev/docs/api/storefront/2025-07/input-objects/CartLineUpdateInput)

  required

  The merchandise lines to update.

  The input must not contain more than `250` values.

***

## Cart​Lines​Update​Payload returns

* cart

  [Cart](https://shopify.dev/docs/api/storefront/2025-07/objects/Cart)

  The updated cart.

* user​Errors

  [\[Cart​User​Error!\]!](https://shopify.dev/docs/api/storefront/2025-07/objects/CartUserError)

  non-null

  The list of errors that occurred from executing the mutation.

* warnings

  [\[Cart​Warning!\]!](https://shopify.dev/docs/api/storefront/2025-07/objects/CartWarning)

  non-null

  A list of warnings that occurred during the mutation.

***

## Examples

* ### cartLinesUpdate reference