So far the calculation is very straightforward as our example vehicle has a receiver height that is greater than the coupler height of the trailer. The result of the equation is simply the amount of drop you need for your hitch. But what if your vehicle’s receiver height is less than the height of the trailer coupler? For that, you will need a riser hitch. Typically a ball mount will be applicable for both a rise and drop. For instance, a 2” drop hitch is also a 3/4” rise; the greater the drop, the greater the rise. [links]