Carpet Calculator — Area, Underlay & Gripper Rod

Our carpet calculator considers the roll width to work out how much carpet you actually need to buy. Because carpet comes in a fixed width off the roll, the calculation is not simply area — you need to factor in the roll width and room orientation.

The formula

If room width ≤ roll width: Carpet length = Room length × (1 + Wastage %)

If room width > roll width: Multiple widths needed, seam required

Carpet area (m²) = Carpet length × Roll width

Underlay and gripper

• Underlay: Standard roll 15m × 1.37m = ~20.5 m² per roll
• Gripper rod: Perimeter minus doorway openings (0.8m per standard door)

For rooms that are wider than the carpet roll, we calculate the number of widths needed and add the extra carpet accordingly. Carpet is priced per m², so knowing the actual area you need to purchase (which may be larger than the room area due to roll width constraints) is important for accurate budgeting.