---
title: "Advanced availability calculation"
url: https://docs.woolytech.com/en/articles/108-advanced-availability-calculation
collection: "How-tos"
updated: 2026-09-02
language: en
---

# Advanced availability calculation

The advanced price modification presents a powerful way to derive prices of the products in the feed, taking inputs from Shopify product price, compare at price, [product and variant metafields](https://help.shopify.com/en/manual/metafields) in [math expressions](https://secure.helpscout.net/article/102-expressions). 

By default, the availability in the feed is derived from product variant inventory using the following rule:

-   _If_ **_track inventory_** _is_ **_not_** _checked, or_ **_variant quantity_** _is greater than 0, item is "in stock_**_"_**
    
-   _Otherwise, if_ **_inventory policy_** _is set to "continue", and there is a value set for the_ **_availability date_**_, item stock status is "backorder"._
    
-   _Otherwise, item status is "out of stock"_
    
    ![](https://staticfiles.gleap.io/helpcenter/65cecc47f9fbfb7f6ae1288e/20260325041346_1171.png)

Do note that the variant quantity can be narrowed down to selected [store locations](https://help.shopify.com/en/manual/locations), which is configured in the Meta tab.

The default expression of availability is sensible for most users' cases. However there are cases you might want to modify it. For example:

Make use of the "preorder" status in Google, with the status provided by a product metafield, and availability date from another.

![](https://staticfiles.gleap.io/helpcenter/65cecc47f9fbfb7f6ae1288e/20260325041346_0095.png)