coil

Thanks for writing in! I'm sorry to say that we would not be able to calculate the weight of the sash based on the size of it. The size does not account for the weight of the glass panes or the framing. 

You'll need to weigh the sash on a scale to get the weight of it. Once you have that weight, you'll divide it by the number of coils in the window to determine the spring strength you'll need.

I hope this helps!