Q: There are a lot of different cell sizes in cellular shades. Why? What are they for?
A: Different cell sizes give you lots of variety in looks AND insulation. Only small cells can be bunched into multiple layers, though, which is especially important if you have a window that gets a lot of sun.
Smaller sized cells make smaller pleats and bigger cells make bigger pleats. You'll want to remember this when you look at the size of your window since smaller pleats look much better on smaller windows than they do on large picture windows. (“Big” cells are usually 1/2” or larger and small cells can be as little as 3/8” across)
I found an exception to this with a cellular shade made by Hunter Douglas that bunches multiple smaller cells in what looks like a single-layer larger-cell cellular shade. It's a remarkable concept because it give you the insulation of multiple small cells but with bigger pleats. You know that big picture window that gets too much sun? Here's your answer!