Multiply the square decimeter number by 0.107639104 to convert to square footage. For example, 15,000 dm^2 multiplied by 0.107639104 converts to 1,614.58656 ft.^2.
Divide the area in square decimeter by 9.290304 to convert to square feet. For example, 30,000 dm^2 divided by 9.290304 converts to 3,229.17313 ft.^2.
Convert the area measurements online at a website like Convert Units (see Resources). Enter the number of square decimeters into the appropriate space and click the "Convert" button --- the equivalent measurement in square feet in the area just beneath it.