How to Calculate Total Square Footage of Your Roof. To find your roof’s total square footage: Measure the length and width of each plane on the roof (including dormers) then multiply length times width. Add the square footage of each of the planes together.
How do you calculate the roof area?
Begin with calculating the area of your house in a plane parallel to the ground. If your house is rectangular, all you need to do is multiply the length and width of the building. If the shape of your house is more complex, simply enter the total area (after measuring the exterior dimensions) into the appropriate box.
Determine the roof pitch of your house. Roof pitch is the slope created by the rafters. If you don’t know how to calculate it, head to our roof pitch calculator. You can input it either in degrees, as a percentage or as a ratio of x:12.
Once you know these values, you will be able to calculate the roof area. Begin by converting the roof pitch to an angle expressed in degrees, using the following formulas:
pitch(%) = x / 12 * 100%
pitch(deg) = arctan[pitch(%)]
Then, use the following equation to find the total area of the roof:
roof area = base area / cos[pitch(deg)]
Tips on measuring for roofing
Measuring your roof’s dimensions is one of the most important aspects of any roofing job, so make sure your tools are up to par. An accurate ruler, tape measure, and a sturdy ladder are all required.
The problem is that not everyone is comfortable with climbing a ladder to do this. What’s more, there is no guarantee that the measurements will be correct. That error can cost you more money, time, and effort.
That’s why it’s best just to hire or consult a professional roofing contractor. They will have the tools, knowledge, and experience to help you accurately measure your roof and figure out how much materials you need with minimal waste.
How to Measure a Roof for Shingles
Don’t worry too much if you don’t know how to measure a roof for shingles. Your roofer will measure the surface of your roof to determine the total square footage, which will dictate how many shingles must be purchased to fully cover the roof’s planes.
But if you’re curious how the measuring process works, think back to your geometry classes in school. To calculate a rough estimate, follow these steps:
- First, you must measure the length and width of each plane of the roof, including dormers. If the planes aren’t rectangles, this may be complicated.
- Next, to calculate the square footage of each rectangular plane, multiply the length by the width. For example, if a plane is 130 feet long and 100 feet wide, it’s 13,000 square feet.
- Finally, add together the square footage of each plane to calculate the total square footage of the roof. So if there are two planes that both measure 13,000 square feet, the total square footage of the roof is 26,000 square feet.