Two of them, both arithmetic
Neither of these decides anything for you. They do the arithmetic that is on the rule pages, with your numbers instead of a worked example, and then they check the answer against what the listings in this catalog actually state. Both print their formula.
Room in feet, rug range in inches
Two sliders for the room and one choice about how the furniture stands. It returns the range a rug wants to fall in and sorts the catalog footprints into inside, below and above it.
6 stated footprints
8 by 10 ft · 5 by 7 ft · 4 by 6 ft · 4 by 5.9 ft · 2 by 6 ft · 2 by 3 ft
Rod height in, panel length out
One measurement from the top of the rod to the floor, plus where the rod hangs and whether you want a hem allowance. It prints the formula and tells you if nothing here reaches.
2 stated lengths
84 in, 7 listings · 63 in, 3 listings