There are two approaches to sell liquids with Loyverse POS.
1. Through selling by weight option
Open your liquid item for editing in the Back Office or Loyverse POS app (Play Market or App Store). Assign the ‘Sold by’ option to ‘Weight’ (How to Sell Items by Weight).
Enter the item price per one liquid measure, for example per one liter (you may indicate the measure in the name of the item, for instance, 'Beer 1L'). Save your edits.
Now, during a sale of such item, a number pad will appear on the screen. Enter the amount in proportion to a liter for the item and tap ‘OK’.
For example, you sell 500 ml of the liquid item, and your measure is a liter. Then you tap 0.5 in the Quantity field.
Then, your item will be added to the ticket with the price shown as the price for a liter multiplied by the actual selling portion. The sold amount will be deducted from the stock for this liquid item.
2. Selling like composite item
If you sell by a particular set of liquid volumes (for example, drinks in shots or pints), you can use composite items.
First, create the component of your liquid item in the 'Item list', and set the amount of stock. If you don’t want to sell this component besides as predefined sets of volumes, deselect the check-box ‘The item is available for sale’ so that it will not be shown in the items list during sales.
Then create your set of liquid volumes from this component item. Each composite item should have the quantity field filled in with the liquid volume.
For example, you are selling Beer by a volume of 500 ml. Create a composite item "Beer 0.5 L". Choose the component ‘Beer’, and set the appropriate quantity. In this case, it is 0.5 L.
Then, with every sale of predefined sets of volume items, the stock of the component of the liquid item will be deducted by the sold amount.
How to Create a Composite Item