

Do this by running your tape measure along the baseboard from one corner to the other.

Look at the room (or outside of the building, if you're taking exterior measurements) and make a rough outline of the dimensions, so you have a good visual starting point. The contractor is going to measure again before ordering materials, so your drawing can be "close enough." If you're doing the work yourself, then be as accurate as possible - measure to the nearest 1/16 inch. If you're simply drawing a preliminary plan to give to a contractor, measure to the nearest 1/4 inch. When space planning an interior remodel, such as a kitchen, you will want to be more precise. Measuring within the nearest 1/4 or even 1/2 foot of outside walls is probably sufficient. If you're a real estate agent or appraiser and your floor plan drawing is simply to measure the approximate size of the building and show the general interior layout, you don't need to be overly accurate.
