Computer Aided Design (CAD) packages such as AutoCAD and Home Designer have tools that allow you to calculate square footage automatically, giving faster, more accurate figures than manual calculation can achieve. Calculating the area in square feet is essential for any number of tasks in planning and design work, from working out materials costs and maintenance regimes to making licence applications and adhering to fire regulations. The exact steps required to make the measurement depend on which CAD package you are using, though the technique is similar regardless of program.
Open your design in AutoCAD. Find the "Object Snaps" or "OSNAP" button -- this is usually at the bottom of the screen. Right click it to open the settings window.
Tick the "Endpoint" box and the "Object Snap On" box. Click OK.
Find the "Command Line," usually above the design window. Type "AREA" in the "Command Line." Use the cursor to click on the corners of the room. Go around the perimeter of the room, clicking each corner in turn, and click again on the first corner. The area in square feet will appear on the command line.
Open the design you want to measure, click the "CAD Configuration Button," which looks like a triangular set square tool. In the menu, click "CAD," and then click "Line." Click "Draw Line," which is a button with a diagonal line across it.
Click and drag a line around the outside of the object you want to measure. Connect the last line to the first line.
Click the "Select Objects" tool, which looks like a white cursor arrow. "Double Click" the line you have drawn. This opens the "Polyline Specification" window. Click the "Polyline Tab." This will display the area in square feet.
Always make sure the lines you draw around an object are connected at the ends, or the calculation will not work. If you are using a different CAD package from those listed, try to modify the approach given in Section 2. Many programs can be used in more or less the same way. Be careful when using this approach to calculate materials costs for things like tiles in irregularly shaped areas. With a regularly shaped room you could just divide its area by the area of the tile to give you the number you will need. In an irregular room, some tiles may have to be cut to shape. The tile offcuts may not be usable anywhere, meaning you will need more tiles than the basic calculation shows you. In practice it is rare to be able to use tile offcuts from one area in another. Rather, a new tile is cut each time. Calculate your needs in this case by drawing grids over the room you are designing, with each square the same size as the tiles you will use. Fit them over the room outline as accurately as possible. Count all the tiles within or cut through by the outlines of the room; do not count those outside it.