Easy to estimate the Hummer materials. A little tougher for most. Build the bubble. Measuring the height and length of the area is a good start. Then you need to add for wheel wells and other peculiarities. I'll usually do a mental doubling of the overall area when building a quote. Maybe adjust that a little up or down based on circumstances. Don't forget their are two of these and that you'll need something like 3 Velcro Strips per side.