Roof Square Metre Calculator
Calculate roof area in square metres from dimensions and pitch. Enter plan area and pitch for actual roof surface area in m², with waste and material quantities. Free, no signup.
Roof Area Calculator
Calculate actual roof surface area from plan dimensions and pitch
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Roof m² - did you know?
Plan m² vs roof m²
Plan area is the footprint. Roof area is the sloped surface. At 35°, 100 m² plan = 122.1 m² roof. The pitch factor (1 ÷ cos(pitch°)) converts between them.
m² to tiles
Tiles needed = m² × tiles_per_m² × (1 + waste%). Concrete: 9-12/m². Clay: 10-15/m². Plain: 60/m². Slate: 20/m². Always check manufacturer coverage.
m² to squares (US)
1 m² = 10.764 sq ft = 0.1076 squares. 100 m² = 10.76 squares → 11 squares (round up). Useful when working with US material specs on metric projects.
Ordering by m²
Suppliers sell roofing by m² coverage. But actual coverage accounts for laps: concrete tile at 10/m² nominal might need 11/m² ordered (10% lap loss). Check "nominal" vs "effective" coverage.
Formulas used
Roof area (m²)
area = plan_m² × (1 ÷ cos(pitch°))
Tiles from m²
tiles = m² × tiles_per_m² × (1 + waste%)
m² to squares
squares = m² ÷ 9.29
m² to sq ft
sqft = m² × 10.764
Frequently asked questions
How do I calculate roof area in m²?
plan_m² × (1 ÷ cos(pitch°)). 100 m² plan at 35° = 100 × 1.221 = 122.1 m² roof.
How many tiles per m²?
Concrete: 9-12. Clay: 10-15. Plain: 60. Slate (500mm): 20. Check manufacturer specs.
How many m² is one square?
1 square = 100 sq ft = 9.29 m². To convert m² to squares: m² ÷ 9.29.
Best free roof m² calculator?
One that calculates from plan + pitch, converts to tiles/squares, and adds waste. This tool does all, free.