Rugs, Carpets and Carpeting - Measuring Area for Carpet Correctly

I've been remodling several rooms in my home lately and I'm almost to the stage where I need to get some carpet on order. I'm a DIYer for just about everything - with the exception of laying carpet and vinyl flooring.

I'm wondering about the correct way to compute the area of each room so I can determine the appropriate amount and roll size.

For example, one of the rooms is a small office that measures 11' 10" wide by 12' 10" deep. The carpet I'm looking at comes in both 12' and 15' wide rolls. What is the correct method for calculating the area and roll size?

Thanks!

well, depending on layout, all carpet needs to face the same direction if the rooms meet on a hall or whatever. you cannot always just determine that a specific room need a 12 x 10 because the room is 11 x 10.

usually if you take the exact sq footage of all areas and add 15% you will be good.
but I draw to 1/4 inch scale then layout my 12 or 15 foot carpet to see if I can allocate waste more efficiently.

a carpet dealer should come out to measure it for you.