How to calculate the LED display size?

Like many newcomers to the LED display, sometimes when they provided an exact size of LED display to the manufacturer, they may feel a little confused when they get back the final screen size because they are slightly different. Here we're trying to explain why and how the final led screen's size come.
The key point is - led module size is fixed, not changeable.
For example of the spec "P6", which means the pixel pitch is 6mm, the module has a fixed size: 192mm×96mm. So when we have decided the pixel pitch to choose, according to the fixed led module size, we can calculate out the final screen size which is closest to the given size. Here I will give you an example for reference:
Suppose the led display size which client requires is 3646(W)×2058(H)(mm), and the pixel pitch we decide to recommend is 6mm, we would know the fixed module size is 192×96(mm). Here is the process to calculate the real and final size:
Firstly, we should calculate how many led modules needed both in width and height. Like this:
The width: 3646/192≈18.98=19
The height: 2058/96≈21.43=21
Then we can calculate out the final size of the screen, like this:
The width: 192×19=3648(mm)
The height: 96×21=2016(mm)
So, the led display screen’s final size is 3648(W) ×2016(H)(mm). 
We assume this is very simple? If you'd like to learn further, please email leddisplayman@foxmail.com