About this calculator
Full tiled-roof takeoff: true roof area, number of concrete or terracotta tiles, battens at the right gauge, sarking rolls, ridge and hip capping, and pointing. Works for gable, hip and mono-pitch roofs.
How it’s calculated
True roof area = plan area including overhang × pitch factor, where pitch factor = √(1 + (rise ÷ run)²). Hip roofs with the same pitch on every side have the same area as a gable over the same footprint. Only the edges differ. Hip length = (half width) × √(2 + (rise ÷ run)²).
Tiles per m² depend on the gauge (exposed length) and cover width of the product. The figures used here are typical. Your tile maker’s gauge table takes priority.
Worked example
With these inputs:
- Roof shape
- Gable (two slopes)
- Building length (wall to wall)
- 10 m
- Building width (wall to wall)
- 8 m
- Overhang (eaves and verge)
- 450 mm
- Pitch entered as
- Degrees
- Pitch in degrees
- 22.5
- Roof covering
- Concrete tiles
- Waste allowance
- 10%
the result is:
- Roof tiles needed
- 1,225 tiles
- Roof surface area
- 105 m²
- Plan area (with overhang)
- 97.01 m²
- Pitch factor
- × 1.082 (22.5°, 4.97/12)
- Eaves length
- 21.8 lin m
Tips from the trade
- Valleys, dormers and chimneys add waste. Go to 15–20% on cut-up roofs.
- Tile fixing (clips, nails or screws) follows AS 2050 and your site’s wind classification. For a metal sheet roof, use the roof sheeting calculator instead.
- Order ridge material for the hips too. It is the most commonly forgotten line.
Common questions
How many roof tiles per m²?
About 10–11 for concrete tiles and 11–13 for terracotta, depending on the profile and the batten gauge.
How much ridge capping do I need?
Measure every ridge and hip. Most capping tiles cover about 370–380 mm each once lapped, so allow about 2.7 per metre.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the NCC and Australian Standards before ordering.