Knowing your roof’s true size is the first step in any roofing project. Quotes, material orders, and repair estimates all start from this one number. This free calculator gives you an honest estimate from simple ground measurements. No ladder needed.
Roof Area Calculator
Measure from the ground. Get your roof’s true surface area in seconds.
Your roof size
Estimate only. Valleys, dormers, and skylights change the real number. Confirm with your roofer before ordering materials.
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Call (409) 290-5353 Serving Texas City & Galveston County, TXHow to measure your roof area without climbing
- Measure your home's length and width along the ground, wall to wall.
- Estimate the eave overhang. This is how far the roof extends past the wall. Most homes have 1 to 2 feet.
- Find your roof pitch. Hold a level 12 inches out from the roof edge and measure how many inches it rises. That number is your pitch.
- Pick your roof shape. A simple gable needs less extra material than a hip roof or a roof with valleys and dormers.
- Enter the numbers above and get your true roof area and roofing squares.
Why your roof is bigger than your floor plan
Two things add area. First, pitch. A steeper roof has more surface than a flat one covering the same footprint. A 6/12 pitch multiplies the footprint by 1.118. A 12/12 pitch multiplies it by 1.414. Second, the overhang. Those extra feet past the walls count as roof surface too. This is why two homes with the same floor plan can need very different amounts of shingles.
Frequently asked questions
What is a roofing square? A roofing square is 100 square feet of roof surface. Roofers and suppliers price materials by the square. If your roof is 1,745 square feet, that is 17.5 squares.
Do I need to climb on my roof to use this? No. Everything here is measured from the ground or estimated visually. The pitch can be judged from a ladder at the eave or even from a photo in many cases.
How accurate is this estimate? It is a solid planning number for standard roofs. Valleys, dormers, skylights, and very cut up designs add waste that a calculator cannot see. Always confirm the final number with your roofer before ordering.
What do I do with this number? Use it to sanity check quotes and to order materials. If you need shingles, run the number through our Roof Shingle Calculator to find how many bundles to buy.If you are weighing a full replacement, here is what a full replacement involves.