Flooring · 7 min read · Beginner

How to Measure a Room for Carpet, Underlay & Gripper

Measure rooms for carpet without relying on floor area alone, and understand roll width, seams, doorways, underlay and gripper requirements.

Key points & steps

Sketch the room first, including alcoves, chimney breasts, bay windows, door recesses and any sections that make the floor shape irregular.
Measure the maximum length and maximum width at the widest points. Carpet is normally ordered as rectangular cuts from a fixed roll width, so the widest dimensions matter even where part of the room is narrower.
Measure alcoves and bay-window projections separately and add them to your sketch rather than assuming the main rectangle covers them.
Check the carpet roll width offered by the supplier. Common roll widths can determine whether the room can be covered in one piece or whether a join is required.
Allow a sensible fitting/cutting margin to each cut rather than ordering exactly to the finished wall-to-wall dimension. Follow the carpet supplier or fitter’s preferred allowance.
Measure floor area separately for underlay, because underlay is normally bought by area rather than by the same cut-length method as carpet.
For gripper, measure the room perimeter where gripper will actually be installed and deduct door openings or sections where gripper is not required.
If the room needs seams, stairs, patterned carpet or unusually shaped cuts, show the sketch and dimensions to the supplier or fitter before ordering because seam position and pattern matching can materially change the quantity.

Do not calculate carpet by simply adding 10% to floor area; a fixed roll width can create much more or much less offcut than an area-only estimate suggests.
Measure each room independently even if several rooms look the same.
Keep your measurements in metres and note which dimension you intend to run across the roll width.