How to Measure a Room for Carpet (UK Guide)

Quick answer: Measure the widest length and width wall-to-wall (include alcoves and doorways), add about 10cm fitting allowance on each side, then use our free carpet estimate calculator for a guide price. Stairs and winders are safest measured by a fitter.

Why measuring carefully matters

Order too little and the job stalls. Order too much and you pay for waste. A simple tape measure and sketch are enough for a calculator estimate — we still confirm sizes on a free home visit before anything is cut.

Step 1: Sketch the room

Draw a rough birds-eye view. Mark the main door, bay windows, alcoves, built-in cupboards and fireplaces. This is your checklist while you measure.

Step 2: Measure the longest length and widest width

Measure wall-to-wall at the maximum points. Include the deepest alcove or window recess. For doorways, measure into the threshold where the carpet meets the next floor. Treat L-shapes as two rectangles and note both.

Step 3: Add fitting allowance

Add about 10cm (4 inches) to length and width. Skirtings are rarely perfect, and fitters need a small trim allowance. Example: 3.82m × 4.15m becomes roughly 3.92m × 4.25m for estimating.

Step 4: Know UK carpet widths

Most carpets come in 4m and 5m widths (some ranges also offer narrower rolls). If your width plus allowance is 3.8m, a 4m roll often fits cleanly. At 4.1m you usually jump to 5m. Visible joins need careful planning — we advise on that during the measure.

Step 5: Check the subfloor while you are there

Note concrete or floorboards, squeaks, and whether underlay needs replacing. New underlay thickness can affect door clearances. See our underlay guide.

Step 6: Stairs and landings

Count treads, note winders or turns, and measure landings separately. Stairs are where DIY measuring goes wrong most often. Book a free home measure across West Sussex if stairs are involved.

Get a free carpet estimate next

Once you have room sizes, use the free carpet cost calculator for an instant fitted guide price. Then we confirm after measuring in Bognor Regis, Worthing, Chichester, Portsmouth and nearby towns.