Measure the length from the gasket to the end of the dip tube. The number you find will give you the total length of the dip tube. Measure the bottle your pump or sprayer goes into. You can do this by measuring from the top of the bottle all the way to the bottom of the container. For bottles with raised bottoms, measure from top to raised bottom. To find out the length of the dip tube that needs to be cut, simply measure the difference between the flat-bottom and the convex-bottom bottle.
This is the Lotion Pumps extra length of dip tube that you don't need. The dip tube can be put into the bottle in two different ways. For most of the thinner dip tubes found on nebulizers, the tube should curve towards the container wall to maximize product dispensing. For the thick dip tubes used by most lotion pumps, the tube can sit in the product with a slight gap to the bottom to allocate space for the product to come out of the container.
