About this calculator
Carpet comes off a roll of fixed width, so you buy a length, not an area. This finds the lay direction that wastes the least, then lists the underlay, gripper and transitions.
How it’s calculated
For each direction: strips = ceil((room width + trim) ÷ roll width); roll length = strips × (room length + trim). The shorter of the two directions wins.
Worked example
With these inputs:
- Room length
- 4.2 m
- Room width
- 3.5 m
- Roll width
- 3.66 m
- Trim allowance per edge
- 75 mm
- Doorways
- 1
the result is:
- Carpet to order
- 15.92 m²
- Lay direction
- along the length
- Strips (seams)
- 1 (0 seams)
- Floor area
- 14.7 m²
- Waste
- 8%
Tips from the trade
- Pile should run the same way in every piece, usually toward the main window or door.
- Keep seams out of the main walking path.
- Carpet is usually priced per lineal metre off a 3.66 m or 4 m roll, so the lay direction changes the price.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the NCC and Australian Standards before ordering.