Category
Roofing Calculators
Convert roof pitch between X/12, degrees and percent, then turn a building footprint into sloped roof area and roofing squares for ordering shingles or underlayment.
Which calculator do I need?
- Roof Pitch Calculator
- Convert roof pitch between the US "X in 12" format, degrees and percentage slope — and get the pitch multiplier and rafter length.
- Roof Area Calculator
- Turn a building footprint and roof pitch into sloped roof area, roofing squares and an estimated number of shingle bundles.
Measuring a roof without climbing on it
You rarely need to walk on a roof to estimate it. Measure the building footprint on the ground, including the eaves and gable overhangs, and find the pitch from the attic, from a ladder at the gable end with an angle finder, or from the plans. The pitch multiplier then converts the flat footprint into the real sloped area.
Roofing materials are ordered in squares of 100 ft² (about 9.29 m²) in North America and by area elsewhere. Every product also has a minimum pitch set by its manufacturer and by building codes, so check that a material is suitable for your slope before comparing prices.
- Add the waste allowance your manufacturer or contractor recommends; hips, valleys and dormers increase it.
- Count ridge, hip and starter materials separately — they are sold by length, not by area.
- Working at height is dangerous: leave roof work to trained people with proper fall protection.