Figuring the square footage of a driveway is an important task if you are planning to pave or enlarge your driveway. Square footage is simply the two-dimensional area covered by a shape or an object. Calculating the square footage of a basic rectangular driveway is a simple process of multiplying length times width. Some driveways, however, have radius entrances. A radius entrance is a curved portion of the driveway that slopes outward toward the road. If your driveway has radius entrances, you will need to apply the appropriate mathematical formulas to determine the total square footage of the driveway.
Sketch a rough drawing of the driveway.
Divide the drawing into three sections. One section is a rectangle that extends from the house outward until you reach the road. The other two sections are on either side of the rectangle. These sections are the radius entrances. They resemble triangles that connect the rectangular portion of the driveway and the road.
Measure the length and width of the rectangular portion of the driveway. Multiply the length times the width to get the area of this section. For example, if the driveway is 12 feet wide and 50 feet long, multiply 12 times 50 to get 600 square feet for this section.
Measure the edge of the driveway that connects the side of the rectangular portion to the end of the outward curve. This edge will be flush with the road.
Square the measurement from Step 4. In other words, multiply the measurement times itself. For instance, if the measurement from Step 4 was 10 feet, multiply 10 times 10 to get 100. Multiply this figure times a constant of 0.2145. In this example, you would multiply 100 times 0.2145 to get 21.45. Multiply this figures times 2 to account for both sides of the driveway. In this example, you would multiply 21.45 times 2 to get 42.9 square feet.
Add the square footage for both sides to the square footage of the rectangular section of the driveway to obtain the total square feet contained within the driveway. In this example, you would add 42.9 to 600 to get 642.9 square feet.