How much carpet do I need for a 4x5 metre room?

For a 4x5m room with a standard 4m wide carpet roll, you need one width of 5m plus waste. At 10% waste allowance, order approximately 5.5 metres of carpet. If the room is wider than 4m, you need two widths, which significantly increases the total. Use the calculator for your exact dimensions and roll width.

How does a carpet pattern repeat affect the amount to order?

When using patterned carpet, each successive width must be shifted by one pattern repeat to match the pattern across the join. This adds waste equal to approximately (number of widths - 1) x pattern repeat length. A 50cm pattern repeat in a two-width room adds 50cm of waste per width - 1 extra metre total. Larger patterns or more widths increase this significantly.

Carpet & Flooring Waste Calculator

Enter your room dimensions, carpet roll width, and pattern repeat to get the exact linear metres to order - including waste for pattern matching. Nothing uploaded.

Total linear metres Pattern repeat waste Roll width widths Offcut size

Room & Flooring Details

Room length (m)

Room width (m)

Carpet / roll width

Pattern repeat (cm, 0 = no pattern)

Waste factor

Order Quantity

linear metres to order

Room area-

Number of widths-

Cut length per width-

Total before waste-

Pattern matching waste-

Total wastage-

Offcut from last width-

Multiple widths needed - ensure all from the same dye lot batch number to avoid visible colour variation.

Learn more: carpet and flooring calculations

Room dimensions and multiple widths

Carpet comes in fixed roll widths: 4m (standard), 5m (wide), 3m (narrow), and vinyl sheet in 6ft (1.83m) or 12ft (3.66m). If your room is wider than the roll width, you need multiple widths seamed together. The calculator calculates how many widths you need and the exact length to order for each. A 4.5m x 3.2m room with 4m wide carpet requires two widths cut to length.

Pattern repeat matching and waste

When using patterned carpet, each successive width must be shifted by one pattern repeat to match the pattern across the join. A 50cm pattern repeat in a two-width room adds 50cm of waste per width - 1 extra metre total. Larger patterns or more widths increase this significantly. The calculator automatically accounts for pattern matching waste and shows you the exact total to order.

Dye lot consistency and colour matching

Carpet colours are not perfectly consistent between production batches (dye lots). Two rolls of the same carpet from different dye lots may have a subtly different shade that is invisible in the shop but immediately visible as a join line when laid side by side. Always confirm all rolls share the same dye lot batch number before accepting delivery. This guide warns you whenever multiple widths are needed.

Waste factor and cutting losses

Flooring always has cutting waste - the basic waste factor accounts for edge trimming and rough cuts. Simple straight rooms may only need 5% waste; complex rooms with many angles or diagonal cuts need 10-15%. Add extra for potential mistakes, seaming loss, or unexpected damage during installation. The calculator lets you adjust the waste factor.

FAQ

How much carpet for a 4x5m room?

With a 4m wide roll: one width of 5m plus 10% waste = approximately 5.5m. If the room is wider than 4m, two widths are needed and cost increases significantly. Enter your exact dimensions for a precise answer.

How does pattern repeat affect the quantity?

Each additional width beyond the first must be offset by one pattern repeat for matching. A 50cm repeat in a two-width room adds approximately 50cm extra to the total order. The calculator accounts for this automatically.

Why does dye lot matter?

Carpet colour varies slightly between production batches. Two rolls from different dye lots may look identical in isolation but show a visible colour difference as a join line when laid. Always order from the same dye lot batch number for any project needing more than one roll.

Last reviewed: June 4, 2026