Roof Size (Squares) Calculator
A roofing square is 100 square feet of roof — the unit roofers price by. To estimate yours, multiply your home's footprint by a slope factor for your roof's pitch (about 1.03 for a low slope up to 1.41 for a very steep one), then divide by 100. Use the calculator below for a rough figure. It's a planning estimate, not a measured take-off.
Estimate your roof size
Enter the footprint your roof covers (roughly your ground-floor area) and pick your pitch. Calculated in your browser.
Turn your roof size into a cost estimate
Once you have a rough roof area, the roof replacement cost calculator turns it into a planning price range by material. Keep in mind this size figure is an estimate — overhangs, dormers, hips, and valleys add area, so a complex roof can run 10–20% larger than the footprint math suggests, and a measured take-off is the only exact number.
Frequently Asked Questions
- What is a roofing square?
- A roofing square is 100 square feet of roof area — the unit roofers use to measure and price a job. A roof with 2,400 square feet of surface area is 24 squares.
- How do I estimate my roof's size in squares?
- Take your home's footprint (the ground-floor area the roof covers), multiply it by a slope factor for your roof's pitch — roughly 1.03 for a low slope, 1.12 for a moderate pitch, up to 1.41 for a very steep roof — then divide by 100. A 2,000-square-foot footprint with a moderate pitch is about 2,240 square feet of roof, or roughly 22.5 squares.
- Why is my roof bigger than my house's square footage?
- Two reasons: the roof is sloped, so its surface area is larger than the flat footprint underneath it, and it extends past the walls at the eaves. That's why roofers measure the actual roof surface in squares rather than using a home's living-area square footage.