How to show free inventory on sales order entry
To enable this feature, toggle ON for the following sales setting (to get there: go to Sales orders > click more on the right):
While on the settings page, press Ctrl+F to find text "free" (without quotes).
Once toggled on, click "Save" at the top.
Free inventory = Current inventory - reserved
Reserved = sales orders have the Confirmed or Part fulfilled statuses
Alternatively, on the order entry page, click "Product" to see more columns on different quantities: