First, measure the width and height of all surfaces you want to cover with film.
You can then use the available film width to plan how many pieces you need and what film length is required.
Also allow for some extra material for cutting, edges and possible waste.
For wood, stone or patterned designs, you should also pay attention to the direction of the pattern. If several fronts are next to one another, it may be useful to allow for some additional film so that the décor creates a harmonious overall look.
A small sketch showing all the required surfaces and measurements will help with planning.