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
- 5.2 m
- Room width
- 4.3 m
- Roll width
- 4 m
- Trim allowance per edge
- 75 mm
- Doorways
- 1
the result is:
- Carpet to order
- 35.6 m²
- Lay direction
- along the width
- Strips (seams)
- 2 (1 seam)
- Floor area
- 22.36 m²
- Waste
- 59%
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.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the Building Regulations before ordering.