When you first set up your POS system you are prompted to add serving sizes for the POS groups imported into Backbar. You can access this page at any time, however, once your POS system is successfully integrated. To do so, just go to the Settings page, under the Sales tab in the side navigation bar. Click on Update your POS groups and default settings. POS mapping and serving size defaults can only be made on the web app.

On the next page, Click the Include? checkbox to toggle the category to include/exclude those items into your Map Items page.  Deselect any categories not being mapped to clear clutter in the mapping step. 

Then, enter the primary serving sizes for each POS group. Set the number and unit under the Default serving size column accordingly - set the toggle to the left if the serving size for that POS group is the whole container (ex. a bottle of wine) or to the right if the serving size is a portion (ex. 5oz). Scroll to the bottom and click Save when you are done.  Note this is the initial serving size for all items in that group, prior to mapping, on the Needs Review tab.

The serving sizes for each item in the Map Items page will be updated according to the POS group they belong to. You'll be able to adjust serving sizes for individual items on the Map Items page after wards if they differ from the default serving.