How to Measure Your Room for Carpet:
A Step-by-Step Guide

Carpet is sold by the linear metre from a roll — either 4 metres wide or 5 metres wide. This is the single most important thing to understand before you measure, because it determines how much carpet you actually need to buy, regardless of your room size.

Step 1: Understand Roll Widths

Carpet comes in two standard roll widths: 4 metres and 5 metres. You cannot buy a piece of carpet that is, say, 3.2 metres wide — you buy the full roll width and cut it to your room length. This means:

• If your room is 3.8m wide, you need a 4m roll (you'll have 20cm of waste on one side)
• If your room is 4.2m wide, you need a 5m roll (you'll have 80cm of waste)
• The "length" you pay for is the room's longest dimension

Always measure in the direction that minimises waste. In most rectangular rooms, this means measuring the longest dimension as your "length" and ensuring the width fits within either 4m or 5m.

Step 2: Measure Length × Width

In the flooring trade, we always quote length first, then width. Measure your room at its longest point (length) and widest point (width), including any alcoves or bay windows that will be carpeted.

Add 10cm to each dimension as a cutting allowance. So a room that measures 4.5m × 3.6m becomes 4.6m × 3.7m for ordering purposes.

Step 3: L-Shaped and Irregular Rooms

For L-shaped rooms, you have two options: order one large piece that covers the entire L (with significant waste in the corner), or order two separate pieces and join them. A professional fitter will advise on the best approach — joins should always be positioned in low-traffic areas and run in the direction of the pile.

Step 4: Stairs

Stairs are measured differently. Each step requires a "tread" (the horizontal surface) and a "riser" (the vertical face). A standard stair tread is approximately 25cm deep and a riser is approximately 18cm high — so each step requires about 43cm of carpet length from the roll.

For a standard staircase of 13 steps, you need approximately 5.6 metres of carpet length from a 4m roll. However, patterned carpets require additional length for pattern matching — always add 15–20% for patterned styles on stairs.

The Easiest Option: Let Us Measure for You

Our free home visit service exists precisely because measuring for carpet is more complex than it looks. Our team will visit your home, measure every room accurately, advise on the best roll width and layout to minimise waste, and give you an exact quote — all at no charge and with no obligation to buy.