Things You'll Need
One of the first steps in building or buying a home is determining how much area you will need. The term "area" is another way of stating "square footage." If you are selling your home, you also will need to report the square footage. You can find the area of a house simply by taking some measurements and performing a few mathematical calculations.
Measure the outer walls of the house using a tape measure.
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Draw a representation of the house on a piece of graph paper. Make the house to scale by sketching it according to your measurements. For instance, you can use a ruler during your sketch and draw each inch to equal 10 feet of actual length.
Divide the drawing into simple shapes. If your house is a perfect rectangle or square, then your work is already done. If not, divide the house into rectangles and squares, preferably, and circles or triangles if necessary.
Multiply the dimensions of each separate shape to find its area. For rectangles and squares, simply multiply length times width. For triangles, multiply the height times the length of the base and then divide by two. For circles, measure from the center of the circle to its edge to find the radius. Then multiply the radius times itself (called "squaring"), and multiply that figure times 3.14 ("pi").
Add the individual areas of each shape to determine the total area of the house.