It's a hard problem. Some stores have half-size paper towels, which I prefer, as paper towels are unnecessary large most of the time. So I want to price-compare based on number of sheets, not cm² ;)
They're not half-size, though, they're actually a bit _more_ than 50%. So that means you'll go through them faster than if you purchase full-sized ones and get in the habit of tearing a full sheet in half and setting the unneeded half aside.
I only want that until someone figures it out and starts making 1/100 size sheets, or some other cheat.
I have the same issue with rice, they always put the price per kg, never per grain..
weight is better for rice since individual grains will vary with size and width.
That's the point, I would only take the biggests.
I just rip off the size of paper towel I need every time I use them.