Firstly, let’s look at how to set up your "by volume/weight button" in the management site. When you create an item, you see a drop down menu against the Sales Price:

The following selections are available, based on how you price the item by weight/volume:

NB: Don't add any mods to an item sold by weight as these items calculate differently than an item sold as one unit. You would need to create a separate item to add on any extras.

Now let’s look at how that works on the posBoss iPad till app.

When you press a menu item with weight/volume, the price per weight/volume appears in the header line along with the calculator - for you to enter in the amount sold. Please note that the weight/volume entered will always be in either grams or millilitres, even if priced by kilogram or litre. Example using litres:

The order/tab appears as follows:

If the button is accidentally swiped and no weight/volume entered, the line item will appear in red as above. You can then delete it or just press the order item it and the calculator will appear again for you to complete.