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.
- Carpet is sold by the square metre or the linear metre off the roll.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and SANS 10400 (the National Building Regulations) and your local municipality before ordering.