Written by the Carpet Flooring Supplies team
Practical guidance for planning a supply-only carpet order and checking the dimensions with your fitter.
Draw the room, measure the maximum length and width into every doorway and recess, and agree a fitting allowance. Then match the required piece to an available carpet roll width, allowing for pile direction, patterns and joins.
Square metres alone do not tell you what to order. A carpet is cut from a fixed-width roll, so the width and length of the piece matter as much as its total area. Measure first, prepare the cutting plan second and have your fitter approve the final order.
What you need before measuring
- A reliable tape measure, or a checked laser measure.
- Paper and a pencil for a labelled floor plan.
- A second person where long measurements need support.
- The exact carpet's available widths and pattern information.
- Your fitter's advice on allowance, joins and pile direction.
Record dimensions in metres, consistently to two decimal places where your measurement supports it. Write 3.84m rather than switching between 3m84cm, centimetres and feet. Never round a tight dimension down.
Step 1: draw the whole room
Sketch the outline from above and mark doorways, bays, alcoves, chimney breasts, columns, fitted cupboards and angled walls. Include any cupboard or recess that will receive carpet. Mark which way doors open and where the carpet meets another floor.
The drawing need not be artistic or precisely to scale. It does need a dimension for each change in shape, so the person planning the cuts can understand where the extra material is required.
Step 2: measure the maximum length and width
Measure to the furthest point the carpet must reach in each direction, including doorway recesses and bays. Take several measurements across the room because opposite walls may not be parallel. Record the greatest actual length and width, then add detail measurements for projections and recesses.
Brockway's measuring guidance recommends a floor plan, inclusion of recesses and bays, and width checks in several places. Use the sketch to record those checks before calculating the order.
A measurement of 4.03m is not 4.00m. A nominal 4m roll cannot simply be stretched to cover a missing width, and you still need the appropriate trimming allowance.
Step 3: agree the fitting allowance
The fitter needs extra material for trimming and positioning. The right allowance depends on the room, carpet construction, pattern and fitting method. Do not add an arbitrary percentage to the floor area and assume it provides extra carpet in the direction where it is needed.
The examples below use an illustrative allowance of 0.10m added to each overall dimension. That means 10cm added to the width and 10cm to the length in total, not 10cm at every edge. It is an example for a straightforward plain carpet, not a universal fitting instruction.
Irregular walls, patterns, seams, stairs or a particular installation method may need a different allowance. Have the fitter set it before the supplier cuts the carpet.
Step 4: choose the roll width and direction
Many domestic carpets come in 4m and 5m widths, but the exact range may have other options or only one width. Check the product you are buying rather than assuming every colour is available in every width.
The required piece must fit within the roll width once the allowance has been added. It may be possible to turn the layout to use another width, but pile direction, pattern orientation, connected rooms and proposed joins can prevent that.
Example 1: a piece that fits a 4m roll
Measured room: 3.82m wide × 4.36m long. Adding 0.10m to each overall dimension gives a required piece of 3.92m × 4.46m.
A nominal 4m roll can accommodate the 3.92m width. If 4.46m is an available order increment and the fitter approves the layout, the carpet order is 4.00m × 4.46m = 17.84m².
The floor area is only 3.82 × 4.36 = 16.6552m², or 16.66m² to two decimal places. The extra purchased material comes from the fixed roll width and fitting allowance.
If the product is sold in larger length increments, round the approved required length up to an available increment. For example, 4.46m would become 4.50m if that product were sold in 0.10m increments, giving 18.00m². Check the actual ordering options.
Example 2: when the direction changes the width choice
A room measures 4.05m × 3.60m. With the same illustrative allowance, the required rectangle is 4.15m × 3.70m.
On a small screen, scroll the comparison table sideways.
| Planned direction | Possible one-piece order | Purchased area |
|---|---|---|
| The 4.15m side must run across the roll | A 4m roll is too narrow. If available and suitable, use 5m width × 3.70m length. | 18.50m² |
| The plan can be rotated so the 3.70m side runs across the roll | A 4m width × 4.15m length may work, if the fitter approves pile and pattern direction. | 16.60m² |
These examples exclude any rounding to the seller's length increments. A 5m roll is one possible solution, not automatically the only solution whenever a room dimension exceeds 4m. Agree the direction before choosing on price.
Step 5: check pile direction, patterns and joins
Carpet can look lighter or darker depending on the direction in which its pile is viewed. Mark arrows on the cutting plan and keep joined pieces in the required direction. A spare piece that fits when rotated is not necessarily usable in that orientation.
For a patterned carpet, obtain its repeat and matching instructions. The extra length needed to align a pattern is separate from a simple trimming allowance. Let the fitter position joins and establish the full quantities; do not assume an offcut can be joined invisibly anywhere in the room.
Colour consistency needs attention too. Cormar explains that different widths and purchases at different times may come from different yarn batches, so a colour match is not guaranteed. Confirm the batch plan with the supplier when ordering adjoining areas.
How to measure L-shaped rooms, bays and alcoves
For an L-shaped room, measure both arms, all corners and the maximum overall length and width. Dividing the floor into rectangles helps check the area, but those rectangles do not automatically make an efficient carpet cutting plan.
For a bay or alcove, record its full width and depth and where it starts along the main wall. Mark whether its front is square, angled or curved. The offcut created elsewhere must have the right dimensions and pile direction if you intend to reuse it.
Keep the outline visible when placing the required pieces on the roll plan. This is where a fitter's check can prevent an apparently adequate square-metre estimate from producing the wrong shape.
How to plan several rooms
Draw and measure each room separately, then plan all the pieces against the selected roll width. Include an allowance for each piece, mark connecting doorways and keep the required pile direction consistent. A large offcut may cover a cupboard or landing, but only if its dimensions and orientation work.
Do not add all the floor areas and divide by the roll width without a layout. That loses the shapes and can hide unusable offcuts. Confirm the full order with the fitter, including joins, batch consistency and delivery access for large pieces.
How to measure stairs and landings
Create a preliminary sketch showing every tread, riser, winder, turn, landing and feature step. Record each step's width and the carpet's route over the tread, around the nosing and down the riser. Do not assume all steps are identical.
Winders, bullnose steps, runners and pattern matching need a detailed plan. Ask an experienced fitter to establish the final quantity and direction. Cormar's fitting guidance also recommends experienced help for stairs.
Calculate the underlay separately and choose a suitable stair underlay. Read our stairs and hallways guide for the specification checks.
How to calculate the carpet material cost
Roll width × ordered length = purchased carpet area. Multiply that area by the current price per square metre.
In example one, a 4.00m × 4.46m cut is 17.84m². At a hypothetical £18 per m², its carpet material cost would be 17.84 × £18 = £321.12.
This is an arithmetic example, not a product quote. The actual total also depends on ordering increments, delivery, underlay, gripper, door bars, fitting and disposal. Use the current product and delivery information for your order.
Calculate underlay separately
Underlay has its own roll width, length and coverage. It can be divided differently from the carpet, so copying the carpet's purchased area may overstate or understate the required number of rolls.
Use How many rolls of underlay do I need? for the calculation. If you are considering keeping existing underlay, read our reuse and replacement guide first.
Final checks before a supply-only order
- The plan includes every doorway, recess and area to be carpeted.
- Maximum dimensions have been checked in more than one place.
- The fitter has set the allowance, direction and any seam positions.
- The chosen carpet is available in the required width, colour and length increments.
- Pattern matching, batch consistency and stairs have been addressed.
- Carpet and underlay quantities have been calculated separately.
- Delivery access and the current order and returns terms have been checked.
- The final cut dimensions have been approved before the order is placed.
Carpet Flooring Supplies sells online on a supply-only basis. Check the delivery coverage for the chosen product and arrange measuring and fitting separately. A piece cut too short cannot be made longer by changing the fitting allowance after delivery.
Frequently asked questions
Do I measure carpet in metres or square metres?
Record length and width in metres. Square metres describe area and are often used for pricing, but the ordered piece must also have the correct roll width and cut length.
How much extra carpet should I allow?
Ask the fitter to set the allowance for the exact room and carpet. The examples here add 10cm to each overall dimension, but patterns, irregular walls, seams and stairs may need more or a different cutting plan.
Will 5m-wide carpet avoid a join?
It can when the required piece fits the available width and length in the correct direction. Check both layout options with the fitter, including pattern, pile direction and access into the property.
What happens if I order carpet too short?
The missing length cannot simply be stretched into place. A repair may need another matching piece and a planned join, and matching material may not be available. Confirming the cut plan before purchase is the better approach.