Estimate plan area, sloped roof area, and a ballpark cost from building size, pitch, and price per square metre.
| Plan area | – |
| Slope area | – |
| Cost | – |
Use this calculator to size a simple gable or hip roof before you order covering. Enter plan length and width, pitch as a percent, and a price per square metre of slope.
Plan area = length × width. Slope factor = √(1 + (pitch/100)²). Slope area = plan × factor. Cost = slope area × price. Length and width can be entered in metres (m) or feet (ft). Areas are shown in m² or ft². A 50% pitch is a 6-in-12 roof (rise/run = 0.5).
This is a single rectangle in plan. It does not add hips, valleys, waste, or a second storey.
Length: Plan length of the roof, in m or ft.
Width: Plan width, in m or ft.
Pitch (%): Rise over run as a percent. 50 means 1:2.
Price per m²: Price per square metre of sloped covering.
Plan area: Horizontal roof area.
Slope area: True roof area on the slope.
Cost: Slope area times the price.
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