---
title: cartLinesUpdate - Storefront API
description: Updates one or more merchandise lines on a cart.
api_version: 2025-10
api_name: storefront
type: mutation
api_type: graphql
source_url:
  html: https://shopify.dev/docs/api/storefront/latest/mutations/cartLinesUpdate
  md: https://shopify.dev/docs/api/storefront/latest/mutations/cartLinesUpdate.md
---

# cart​Lines​Update

mutation

Updates one or more merchandise lines on a cart.

## Arguments

* cart​Id

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

  required

  The ID of the cart.

* lines

  [\[Cart​Line​Update​Input!\]!](https://shopify.dev/docs/api/storefront/latest/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/latest/objects/Cart)

  The updated cart.

* user​Errors

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

  non-null

  The list of errors that occurred from executing the mutation.

* warnings

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

  non-null

  A list of warnings that occurred during the mutation.

***

## Examples

* ### cartLinesUpdate reference

## Mutation Reference

```graphql
mutation cartLinesUpdate($cartId: ID!, $lines: [CartLineUpdateInput!]!) {
  cartLinesUpdate(cartId: $cartId, lines: $lines) {
    cart {
      # Cart fields
    }
    userErrors {
      field
      message
    }
    warnings {
      # CartWarning fields
    }
  }
}
```

## Input

```json
{
  "cartId": "gid://shopify/<objectName>/10079785100",
  "lines": [
    {
      "id": "gid://shopify/<objectName>/10079785100",
      "quantity": 1,
      "merchandiseId": "gid://shopify/<objectName>/10079785100",
      "attributes": [
        {
          "key": "<your-key>",
          "value": "<your-value>"
        }
      ],
      "sellingPlanId": "gid://shopify/<objectName>/10079785100"
    }
  ]
}
```