---
title: cartLinesAdd - Storefront API
description: >-
  Adds one or more merchandise lines to an existing

  [`Cart`](/docs/api/storefront/2026-10/objects/Cart). Each

  line specifies the [product
  variant](/docs/api/storefront/2026-10/objects/ProductVariant)

  to purchase. Quantity defaults to `1` if not provided.


  You can add up to 250 lines in a single request. Use
  [`CartLineInput`](/docs/api/storefront/2026-10/input-objects/CartLineInput)

  to configure each line's merchandise, quantity, selling plan, custom

  attributes, and any parent relationships for nested line items such as

  warranties or add-ons.
api_version: 2026-10
source_url:
  html: 'https://shopify.dev/docs/api/storefront/latest/mutations/cartLinesAdd'
  md: 'https://shopify.dev/docs/api/storefront/latest/mutations/cartLinesAdd.md'
api_name: storefront
api_type: graphql
type: mutation
---

# cart​Lines​Add

mutation

Adds one or more merchandise lines to an existing [`Cart`](https://shopify.dev/docs/api/storefront/2026-10/objects/Cart). Each line specifies the [product variant](https://shopify.dev/docs/api/storefront/2026-10/objects/ProductVariant) to purchase. Quantity defaults to `1` if not provided.

You can add up to 250 lines in a single request. Use [`CartLineInput`](https://shopify.dev/docs/api/storefront/2026-10/input-objects/CartLineInput) to configure each line's merchandise, quantity, selling plan, custom attributes, and any parent relationships for nested line items such as warranties or add-ons.

## Arguments

* cart​Id

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

  required

  The ID of the cart.

* lines

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

  required

  A list of merchandise lines to add to the cart.

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

***

## Cart​Lines​Add​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

* ### cartLinesAdd reference