# Set stock levels from an external system

> Overwrite available stock per item and location with inventorySetQuantities, using changeFromQuantity and an idempotency key as 2026-10 requires.

Page: https://lintelagency.com/resources/graphql/set-inventory-quantities

## In short

To set stock from an ERP or warehouse system, call inventorySetQuantities with name available (or on_hand), a reason such as correction, and a list of quantities per inventory item and location. From 2026-04, each quantity needs changeFromQuantity (the value you expect Shopify to have, or null to skip the check) and the mutation needs an @idempotent key.

## Facts

- **API:** Admin GraphQL API
- **Operation:** inventorySetQuantities
- **Access scope:** write_inventory
- **Replaces (REST):** POST /admin/api/inventory_levels/set.json
- **API version:** 2026-10
- **Last checked:** 2 November 2026

## How to use it

1. Look up the inventory item IDs (on each variant’s inventoryItem) and the location IDs once, and store them next to your SKUs.
2. For each item, send the new quantity and the quantity you last saw as changeFromQuantity.
3. Generate a new idempotency key (a UUID) per change and pass it with @idempotent. Retry a failed request with the same key.
4. If userErrors returns CHANGE_FROM_QUANTITY_STALE, read the current level and decide again instead of forcing the value.

## Code

### inventory-set-quantities.graphql

```graphql
mutation SetStock($input: InventorySetQuantitiesInput!, $idempotencyKey: String!) {
  inventorySetQuantities(input: $input) @idempotent(key: $idempotencyKey) {
    inventoryAdjustmentGroup {
      reason
      referenceDocumentUri
      changes {
        name
        delta
        quantityAfterChange
      }
    }
    userErrors {
      code
      field
      message
    }
  }
}
```

### inventory-set-quantities.variables.json

```json
{
  "idempotencyKey": "6f1c2b9e-3d4a-4f7e-9b1a-2c3d4e5f6a7b",
  "input": {
    "name": "available",
    "reason": "correction",
    "referenceDocumentUri": "gid://your-erp/StockSync/2026-11-02-0900",
    "quantities": [
      {
        "inventoryItemId": "gid://shopify/InventoryItem/1111111111",
        "locationId": "gid://shopify/Location/1234567890",
        "quantity": 12,
        "changeFromQuantity": 10
      },
      {
        "inventoryItemId": "gid://shopify/InventoryItem/1111111112",
        "locationId": "gid://shopify/Location/1234567890",
        "quantity": 0,
        "changeFromQuantity": 3
      }
    ]
  }
}
```

### inventory-set-quantities.response.json

```json
{
  "data": {
    "inventorySetQuantities": {
      "inventoryAdjustmentGroup": {
        "reason": "Inventory correction",
        "referenceDocumentUri": "gid://your-erp/StockSync/2026-11-02-0900",
        "changes": [
          {
            "name": "available",
            "delta": 2,
            "quantityAfterChange": null
          },
          {
            "name": "on_hand",
            "delta": 2,
            "quantityAfterChange": null
          },
          {
            "name": "available",
            "delta": -3,
            "quantityAfterChange": null
          },
          {
            "name": "on_hand",
            "delta": -3,
            "quantityAfterChange": null
          }
        ]
      },
      "userErrors": []
    }
  }
}
```

## Limits and edge cases

- name accepts only available or on_hand. Setting available also moves on_hand by the same delta.
- reason must be one of Shopify’s values, such as correction, cycle_count_available, received or restock. referenceDocumentUri shows in the inventory history.
- Use this only when your system is the source of truth. For relative changes, such as a sale in another channel, use inventoryAdjustQuantities.
- Passing changeFromQuantity: null turns the check off; concurrent updates can then overwrite each other.

## Questions

### How do I update inventory in Shopify with GraphQL?

Use inventorySetQuantities to set an absolute number, or inventoryAdjustQuantities to add or remove units. Both work per inventory item and location.

### What is changeFromQuantity?

The quantity you expect Shopify to have before your change. If it differs, the update is rejected, so a sale that happened in between isn’t lost.

### Why do I get an idempotency key error?

From API version 2026-04 the mutation requires @idempotent(key: ...). Use a new key per change and the same key when retrying it.

### Where do I find the inventory item ID?

Each variant has an inventoryItem with its own ID. Query productVariants or the variant by ID and select inventoryItem { id }.

## Shopify documentation

- [inventorySetQuantities](https://shopify.dev/docs/api/admin-graphql/latest/mutations/inventorySetQuantities)
- [Manage inventory quantities and states](https://shopify.dev/docs/apps/build/orders-fulfillment/inventory-management-apps/manage-quantities-states)
- [Idempotent requests](https://shopify.dev/docs/api/usage/idempotent-requests)

## Related

- [Read stock levels by location](https://lintelagency.com/resources/graphql/inventory-levels-by-location)
- [Keeping inventory in sync with another system](https://lintelagency.com/journal/sync-inventory-external-system)

License: MIT. Free to use in your own store and in client work.