TO USE THE QUOTE TOOL, YOU WILL NEED TO START BY TAKING TWO MEASUREMENTS:
Measure the area of the room you will be installing flooring in.
once you have the tiled area total, re-measure the room omitting permanent objects like tubs, toilets, cabinets, heat vents and drains.
The remaining areas combined, are the heated area.
keep in mind the quote tool will factor in wall spacing for you.
here is an example: