To add a new a pack size, first go into your Inventory and select the product.
Once you are on the variant page, select the variant and then choose “Add a Pack Size" from the dropdown options.
You then need to create a label for the Pack size. Add the Pack size Quantity.
The wholesale, retail and buy prices are auto-filled, as a multiple of the variant prices. However you can edit the pack size prices.
Save the pack size. The pack size has been created.
Once the pack size is created you will see that the available stock for the pack sizes would be in multiples according to the packsize quantity.
Under pack size details you will see that the sku is inherited from the variant, but you can add custom information such as the barcode and supplier code. You can also add in the size and weight of the item.