How to Calculate the Area & Scale for Building Plans

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Things You'll Need

  • Sheet of paper

  • Tape measure

  • Pencil


Whether you are designing a new house or designing a new deck, one of the first steps is to create a building plan. Building plans aren't drawn to size, they are drawn to scale, which means that you "shrink" the area down and make a scale model on paper. How much to scale down depends on how large the plan is, how detailed you want those plans and how big your paper is.


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Step 1

Measure the longest part of your building project, in feet. For example, the projected length of your house is 30 feet.

Step 2

Measure the longest part of your paper, in inches. For example, the length of your paper is 10 inches.


Step 3

Divide step 1 by step 2. 30 feet / 10 inches = 3 feet / inch This means that every 1 inch of paper space represents 3 feet of "real" length.


If you have an unusually long building plan, you may want to consider purchasing a roll of paper, which you can cut to size for your plan, rather than having half of the paper space empty. Add a few feet of length around the edge of your building project if you want a border around the edge. Use your scale drawing to calculate area by converting to “real” measurements before multiplying length by width. For example, if on paper, an area is 5 inches by 5 inches, then 5(3) = 15 feet, so 15 feet by 15 feet = 225.