How to Calculate Square Footage of Your Roof

The total cost of your roofing job is determined by square footage, pitch of your roof, and the materials you want – but don’t worry, even if you didn’t get an A+ in high school geometry and algebra, you can do the math.

To estimate the cost of a major roof repair or replacement you’ll need to figure out the square footage of your roof. For this, you need to know your roof’s base area and the angle.

1. Your first task is to stop looking up – and start looking down. Measure the ground dimensions of your house using a tape measure. Then, multiply length times width to get the ground area. Your house probably isn’t a perfect square or rectangle, so take each square piece one by one. Figure out the separate areas and then add them together.
2. Once you have the ground area, convert that number to roofing squares. One roofing square equals 100 square feet of roof. So, divide your total ground area by 100 – that is how many roofing squares your roof will need.
3. Estimating the pitch of your roof is much easier than your high school geometry class – we promise! In fact, roof pitches come in 3 categories: Low, Medium, and High. A high pitch roof rises more than 9 inches for every 12 inches of base horizontal length; medium pitch rises 6-9 inches, and a low pitch rises 3 inches for every foot of horizontal length. To find out your pitch, grab a level and a tape measure and climb a ladder to where your roof begins. Hold the level horizontally, about a foot from the bottom of the roof. Find the 12 inch mark on the level, and measure straight down to the roof using the tape measure.
4. For a low-pitch roof, multiply the number of roofing squares by 1.06 to 1.08 to get the square roof area. For a medium pitch roof, multiply by 1.12 to 1.25; and for a high pitch roof, multiply by 1.3 or 1.4.

To make life easier, we have a Free Roofing Estimate Calculator! Just enter in your roof square footage, your roof pitch, and roof type and we will send you our estimate.