An In-Depth Guide on Measuring for Carpet: From Rooms to Stairs
Why It’s Important to Measure Your Carpet Correctly
Measuring might seem like a simple task, but its importance cannot be overstated. Here’s why getting it right from the start is crucial:
Cost Efficiency: Under-ordering is a huge problem — you can't just add a small strip. Over-ordering means you've wasted money on carpet you don't need. Correct measurements ensure you buy exactly what's required, plus a small amount for trimming.
Minimising Seams: Carpet comes in standard roll widths (usually 4m and 5m). By measuring your room's widest points, you or your fitter can plan the installation to use the fewest possible seams. Fewer seams result in a more professional and durable finish.
Avoiding Installation Day Disasters: There is nothing worse than having a fitter arrive only to discover the carpet you purchased is too small. This leads to costly delays, reordering, and disappointment.
Pattern Matching: For patterned carpets, accurate measurements are even more critical. You need to account for the "pattern repeat" to ensure the design lines up perfectly across seams, which often requires ordering extra material.
Key Issues & Problems People Run Into
Even with the best intentions, mistakes can happen. Here are the most common pitfalls to watch out for when measuring for carpet.
| Common Problem | The Consequence | The Solution |
|---|---|---|
| Forgetting Alcoves & Doorways | The carpet piece will be too narrow or short to fit the room's maximum dimensions, making it unusable. | Always measure the widest and longest points of the room, including the depth of any alcoves, bay windows, and into the doorway threshold. |
| Assuming a Room is Square | You measure one wall and assume the opposite wall is the same length. Rooms are rarely perfect rectangles. | Always measure both sides for length and width and use the larger of the two measurements for your calculations. |
| Not Adding a Trimming Allowance | The carpet piece is exactly the size of the room, leaving no margin for error or for trimming against uneven walls. | Always add at least 10cm (4 inches) to both your final length and width measurements. This is your safety net. |
| Ignoring Carpet Pile Direction | The pile direction affects the colour and sheen. If pieces are laid in opposite directions, they will look like two different colours. | All pieces of carpet in a single area must be laid with the pile running in the same direction. This must be factored into your cutting plan. |
| Incorrect Stair Measurements | You end up with a runner that's too short or not wide enough to cover the steps properly. | Stairs require a very specific measuring technique. Follow the detailed guide below and double-check your maths. |
Required Tools & Equipment
You don't need a professional's toolkit, but having the right basic equipment will ensure accuracy and make the job much easier.
| Tool / Equipment | Purpose |
|---|---|
| Metal Tape Measure | A 5m or 8m metal tape measure is essential. Fabric tapes can stretch and give inaccurate readings. |
| Notepad & Pen/Pencil | To draw a floor plan and write down all your measurements. Don't rely on memory! |
| Calculator | To do the final calculations and add your cutting allowance without making mistakes. |
How to Measure a Room for Carpet: Step-by-Step
For square or rectangular rooms (even those with alcoves), follow this simple process.
Step 1: Draw a Simple Floor Plan
Start by sketching a basic "bird's-eye view" of the room. It doesn't need to be artistic, but it should include the main shape of the room plus any alcoves, fireplaces, bay windows, and doorways.
Step 2: Measure the Maximum Width and Length
● Width: Measure the distance from wall to wall at the widest point of the room. If you have an alcove or a fireplace that juts out, make sure you are measuring the absolute maximum distance.
● Length: Do the same for the length, measuring the longest distance from one end of the room to the other.
● Important: Measure into any doorways to the point where the carpet will finish (usually under the centre of the closed door). Write these two key measurements on your floor plan.
Step 3: Add Your Cutting Allowance
Once you have your maximum length and width, add 10cm (4 inches) to each measurement.
● Example: If your room measures 3.5m x 4.2m, your required carpet size will be 3.6m x 4.3m.
Step 4: Consider the Carpet Roll Width
This is a crucial final check. Carpets are typically sold in standard widths, most commonly 4 metres and 5 metres.
● If your room's widest measurement is 3.8m, you will need to buy a 4m roll. Your total order would be a piece that is 4m (the roll width) by [Your Measured Length + 10cm].
● If your room's widest measurement is 4.5m, you cannot use a 4m roll (unless you add a seam). You would need to buy a 5m roll.
How to Measure Carpet for Stairs: The Complete Guide
Measuring stairs is more detailed but perfectly achievable. We'll cover two scenarios.
Scenario 1: Straight Stairs
Measure a Single Step: You need two measurements per step:
○ The Tread: The flat part you step on.
○ The Riser: The vertical part of the step.
○ Measure the depth of one tread and the height of one riser. Add them together. For example, if the tread is 25cm and the riser is 20cm, your total is 45cm.
Add for the 'Nose': Most steps have a rounded "nose" that overhangs the riser. Add an extra 2cm to your measurement per step to account for this. So, 45cm becomes 47cm.
Multiply by the Number of Steps: Count the number of stairs and multiply that number by your per-step measurement.
○ Example: 13 stairs x 47cm per step = 611cm (or 6.11m). This is your total required length.
Measure the Width: Measure the width of a single step. This is your required width.
Add Your Cutting Allowance: Add at least 10cm to both your final length and width measurements.
Scenario 2: Stairs with a Landing or Winder (Turning Steps)
● For the Straight Steps: Measure them exactly as described above.
● For the Landing: Measure the landing as if it were a small, separate room. Measure its maximum width and maximum length, and add 10cm to each dimension.
● For Winder/Kite Steps (the triangular turning steps): These are the trickiest. To be safe, treat each window step as a rectangle. Measure the widest point of its tread and its longest point of the riser. Calculate the carpet needed for each window step individually and add it to your total length.
Pro Tip for Stairs: The carpet pile should always run down the stairs. This helps it wear better and provides more grip. This may affect how the carpet is cut from the roll.
Frequenty Asked Questions (FAQs)
Q: How much extra carpet should I buy?
A: As a rule of thumb, add 10cm (4 inches) to your final length and width measurements for a cutting allowance. Some people calculate the total area (m²) and add 10%, but the "add 10cm to each dimension" method is safer for ensuring the single piece is large enough.
Q: What are the standard carpet widths in the UK?
A: The most common standard roll widths are 4 metres and 5 metres. A very limited selection may be available in other widths, but planning for 4m or 5m is your best bet.
Q: Do I need to measure for underlay and carpet grippers separately?
A: Yes, but you can use the same room measurements. Calculate the total square meterage (Length x Width) for your underlay. For grippers, you need to measure the perimeter of the room (add all wall lengths together), but subtract the width of any doorways.
Q: I have a patterned carpet. Do I need to measure differently?
A: Yes. You must account for the pattern repeat. This is the distance before the pattern starts over. You will need to order extra carpet (often an extra 10-15%) to ensure your fitter has enough material to align the pattern perfectly across any seams and on stairs. Check the pattern repeat length with the manufacturer.
Q: Should I just get a professional to measure?
A: Most reputable carpet retailers offer a free measuring service. This is a great, risk-free option. However, learning to do it yourself is a valuable skill, empowers you to shop around for quotes online, and helps you double-check any professional measurements to understand exactly what you're paying for.