How do I measure a room for carpet?

Measure the length and the width of the room at their widest points and multiply them for the floor area. Add a waste allowance because carpet comes in fixed width rolls and needs trimming, and seams have to line up. The calculator adds the allowance for you.

Why is there waste with carpet?

Carpet is made in set roll widths, usually 3.66 metres, so cutting a room to fit almost always leaves offcuts. Hallways, stairs, and pattern matching add more. A 10% allowance is a sensible starting point, but your installer will measure exactly.

Does the price include underlay and fitting?

This calculator costs the carpet only, from the price per square metre you enter. Underlay, smoothedge, delivery, and installation are usually extra, so ask for a full quote that includes them.

Carpet Calculator

This calculator works out how much carpet you need for a room and roughly what it will cost, so you can budget before you order or get quotes. Enter the room's length and width in metres, a waste allowance as a percentage, and the price per square metre you have been quoted or are budgeting for. The waste allowance matters because carpet comes off a roll of fixed width, usually 3.66 metres, so trimming, seams and pattern matching mean you always order more than the bare floor area; 10% is a reasonable starting point for a simple room, though hallways, stairs and odd angles need more. The calculator returns the floor area, the area to order once waste is added, and the estimated carpet cost from your price per square metre. For example, a 4.5 by 3.6 metre room comes to 16.2 square metres of floor, about 17.8 square metres to order with 10% waste, and roughly $1,336 in carpet at $75 a square metre. Adjust any figure and the results update instantly, so you can compare room sizes, waste allowances or carpet prices side by side. Keep in mind this covers carpet only; underlay, smoothedge, delivery and fitting are usually charged separately, so treat the total as an indicative estimate for planning, and confirm exact quantities and pricing with your carpet supplier or installer.

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Room length (m)

Room width (m)

Waste

Price per m²

estimated carpet cost

Floor area0 m²

Order (with waste)0 m²

Carpet only. Underlay, smoothedge, delivery, and fitting are usually extra.

How it works

The floor area is the length times the width. Because carpet comes in fixed width rolls and needs trimming and seam matching, a waste allowance is added, often around 10%. The cost is the area to order times the price per square metre.

Worked example

A 4.5 by 3.6 metre room is 16.2 square metres. With 10% waste you order about 17.8 square metres. At $75 a square metre, the carpet is about $1,336, before underlay and fitting.

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