When you run soft serve mix in your soft serve machine, your equipment has the ability to add air to the finished product. Let’s say you have a gravity machine and you add your mix into the hopper (top of the machine). You will have a feed tube that mixes air and soft serve mix together as it draws product into the freezer. Most gravity machines will add 35% air to your mix creating volume to the soft serve product you serve. The weight never changes. Some companies will use volume numbers to minimize the cost of their mix. We recommend you always use weight as a guideline for your per ounce serving cost when comparing the cost of mix. The weight of a gallon of mix is a good starting point.