Roof squares calculator
Footprint and pitch in, roof area in squares out — plus the bundles, underlayment and trim to order. No sign-up, no email.
The roof
The ground the roof covers, not the roof surface.
6 means 6/12. Multiplier 1.118.
10% on a simple roof; 15%+ when it is cut up with valleys and hips.
Linear measurements — optional
Fill these in and you get drip edge, starter, ridge cap and ice & water too.
Your numbers
Materials
Coverage figures are the common ones — check them against your own products before ordering, because bundle and roll coverage varies by manufacturer.
This is the arithmetic. RidgeSync does it from your own catalog — your products, your coverage, your costs — straight into a priced quote and a material order.
Try it free for 30 daysHow the maths works
A roof plane is a slope over a horizontal run, so its true area is always larger than the footprint beneath it. The pitch multiplier is the hypotenuse of a right triangle with a 12″ run: √(rise² + 12²) ÷ 12. At 6/12 that is 1.118, at 12/12 it is 1.414.
Multiply the footprint by that, divide by 100, and you have your squares. Add waste to the area goods only. Linear items — drip edge, starter, ridge cap, ice & water — come off eaves, rakes, ridges and valleys and get rounded up to whole sticks and rolls, because you cannot buy 4.3 of a 10-foot stick.
Common questions
What is a roofing square?
One square is 100 square feet of roof surface. Shingles are sold and estimated in squares — a 2,400 sq ft roof is 24 squares. Suppliers quote in squares, so it is the number every other figure comes off.
Why can't I just use the size of the house?
Because the roof is bigger than the ground it covers. A pitched plane is the hypotenuse over the horizontal run, so you multiply the footprint by the pitch multiplier — 1.05 at 4/12, 1.12 at 6/12, 1.41 at 12/12. Skip it on a steep roof and you under-order by a fifth.
How much waste should I add?
10% on a simple gable is the usual starting point, 15% or more once the roof is cut up with valleys, hips and dormers. Waste belongs on area goods — shingles and underlayment. Trims and linear items get rounded up to whole pieces instead.
How many bundles are in a square?
Three, for most architectural shingles. Check your own product — some heavier profiles run four to the square, and that difference across a whole roof is a supply run you did not plan.
Where does ice & water shield go?
Eaves and valleys, plus wall and step flashings. Not rakes — a rake has nothing draining onto it. Getting this wrong is one of the most common ways a material order comes out short.
Stop doing this by hand
RidgeSync runs this off your own catalog — your products, your coverage, your costs — from a measurement report, a hand measurement or a photo, straight into a priced quote and a material order. $149/mo flat, unlimited users, no per-report fees.