Measuring the height of the ceiling for sloped ceiling could be frustrating since the height is different along the ceiling. You need to find either the highest point or lowest point where the slat is going to touch the ceiling.
We will include a 3D printed jig (custom made to your ceiling slope) in your order free of charge. You will find the highest and lowest point of the ceiling where the slat is going to be installed by placing this jig on the ceiling bracket. Alternatively, you can measure distance from the floor to the bottom of the jig, and add the hight of the jig to get the required length of the slat.