Roofing calculators
Two calculators for planning a re-roof: the materials and cost range, and the pitch figures that drive them.
Calculators in this category
Why pitch matters
A roof is larger than the floor plan underneath it, and the steeper the pitch the larger it gets. The pitch multiplier converts the flat footprint into the sloped area that needs covering. A low 4/12 roof adds about 5% to the plan area, while a steep 12/12 roof adds about 41%. Getting the pitch right is the biggest single factor in a roofing estimate.
Squares, bundles and tiles
In North America, roofing is counted in squares of 100 square feet, and asphalt shingles are usually packed three bundles to a square. In the UK and much of Europe, pitched roofs are more often covered with concrete or clay tiles or slate and priced per square metre. The roofing calculator gives the area in both systems so you can compare quotes either way.
What a roofing quote should list
A clear quote states the roof area in squares or square metres, the material and its brand, whether old layers are removed, the underlayment or membrane, flashing, ventilation, gutters if included, disposal, permits and the warranty. Comparing quotes line by line against your own estimate makes it easy to see which ones leave something out.
Leave the roof work to professionals
Working at height is one of the most common causes of serious injury in home improvement. Use these tools to understand the size of the job and to check quotes, and hire a licensed, insured roofer for the work itself. Ask whether the quote includes tear-off, disposal, flashing and ventilation.