How to Measure Stairs for Carpet in the UK

How to measure stairs for carpet: start with a sketch

Draw the staircase before taking measurements. Mark the bottom and top, every step to be carpeted, any winding steps, and each landing or half-landing. Note where the carpet will start and finish, because a flight that ends at a doorway may need a different finish from one that continues across a landing. Give each flight and landing its own label so the figures cannot be mixed up later.

Decide whether the carpet will cover the full stair width or form a narrower runner. For a runner, record the intended exposed margin on both sides as well as the proposed carpet width. Photograph changes in shape, such as a curved nosing or a step wider than its neighbours. These details help a fitter check whether a simple length calculation reflects the actual job.

Label every flight, landing and turn on the sketch.
Mark the intended carpet edges and any doorway finish.
Keep all recorded dimensions in millimetres.

Gather tools and check what will be fitted

Use a tape measure with clear millimetre markings, a pencil and a written measurement sheet. A flexible tape is useful where you need to follow the curve over a stair nosing. Measure the staircase itself, not an existing carpet whose edges may have moved or been trimmed. If old flooring will be removed, tell the fitter what is currently underneath it.

Ask whether the quote includes carpet, underlay, gripper rods, stair rods or a separate landing piece. These are different items, and their fitting arrangements can affect where carpet starts, ends or joins. Measure visible surfaces for the carpet calculation, but do not assume the same dimensions are an underlay cutting list. A fitter should confirm those details for the chosen product and installation method.

Measure the width of every flight

Measure from one side of a tread to the other at the front, middle and back of the flight. Repeat at the top, bottom and anywhere the staircase looks narrower or wider. Record the smallest and largest widths instead of silently choosing one figure. Skirting boards, stringers and uneven walls can make the usable width different from the apparent width.

For a runner, measure the intended visible carpet width and check the exposed margin on both sides at several steps. For a full-width carpet, give the fitter the actual widths and let them confirm the cutting width and edge treatment. Do not add an arbitrary percentage to a width and treat it as a finished specification. Pattern alignment, trimming and the method of fitting can all affect the required cut.

Measure each tread and riser along the carpet path

Measure the tread from its back edge towards the front, then continue over the nosing to the point where the carpet will turn down the riser. Measure down the riser to the next tread. Record the combined tread-and-riser length for each covered step, or record the two parts separately and add them later. Following the surface path matters because a flat horizontal measurement misses the carpet needed to pass over the nosing.

Do not assume every step is identical, even on a straight flight. Check at least several steps individually, then measure every step that appears different in depth, rise or nosing shape. For the most reliable order check, record every covered step and add the measured lengths. Count the covered steps twice against the sketch, especially where the top floor or a landing forms the final walking surface.

Measure along the surface the carpet will cover.
Record tread and riser dimensions for each covered step.
Check the step count against the staircase sketch.

Treat landings and turns as separate pieces

Measure each landing's length and width at more than one point. Mark doorways, thresholds and the line where the stair carpet is expected to meet the landing carpet. A landing is a floor area, not another standard tread-and-riser pair. Keep its dimensions separate until the fitter has decided where cuts or joins will go.

For winding or tapered steps, record the depth at the inner edge, centre and outer edge, together with the width. Sketch the direction of the turn and label each step in order. A single centre-line length does not describe the shape needed to cut those pieces. Ask the fitter to inspect the measurements or visit before ordering carpet for a turning staircase.

Add the lengths and check the proposed order

For a straight flight, add the measured tread-and-riser lengths of the covered steps. Keep landing dimensions separate and write any proposed fitting allowance as its own line, rather than hiding it in a rounded total. This makes the arithmetic easy to check and shows what still needs the fitter's approval. Record the date and measurement units beside the total.

The length of a flight is not, by itself, an order quantity. Carpet is supplied in roll widths, and the cutting plan must account for the chosen carpet's width, pile direction, pattern and possible joins. Give the supplier or fitter the sketch, individual dimensions and calculated flight length. Ask them to confirm the required cut sizes and allowances before paying for material.

Final verification checklist

Walk the staircase once more with the sketch in hand. Check that every carpeted step appears exactly once, that landings have their own measurements, and that widths match the intended full-width carpet or runner. Re-measure any figure that looks unusual beside its neighbours.

Compare your written totals with the original dimensions rather than relying on memory. Confirm with the fitter where the carpet will start, end and join, and who is responsible for final cut sizes. Keep the agreed measurements with the quote so later changes are clear.

Step count and tread-and-riser totals checked.
Narrowest and widest points recorded.
Landings, turns and thresholds marked separately.
Cut sizes, joins and allowances confirmed by the fitter.

Reproducible worked record

Illustrative straight-flight length check

All numbers in this example are illustrative, synthetic measurements, not dimensions or allowances recommended for a real staircase.

Covered steps: 12 illustrative identical tread-and-riser sets
Surface length per tread: 250 mm, illustrative
Surface length per riser: 190 mm, illustrative
Example allowance for arithmetic only: 100 mm at each end, illustrative and subject to fitter approval

Calculation

(250 mm + 190 mm) × 12 = 5,280 mm measured flight length; 5,280 mm + 100 mm + 100 mm = 5,480 mm illustrative planning length.

Result

The arithmetic confirms the example flight-length total; it does not establish a suitable carpet cut size or order quantity.

Verification boundaryRecount the covered steps, re-measure each tread-and-riser path, add the recorded lengths individually, and have the fitter confirm any allowance.

References and field record

Check the assumptions at their source.

The UK government's Approved Document K provides official context for stair terminology and construction; the illustrative carpet arithmetic is a measuring method, not a requirement stated in that document.

UK govOfficial context for stair terms and features, including flights, landings, treads and risers; it does not prescribe carpet ordering allowances.
Protection from falling, collision and impact: Approved Document K

Download the field measurement record

References checked August 6, 2026. External specifications can change; verify the current document before relying on a product or regulated dimension.

Scope and limitations

This note helps householders organise measurements and understand the calculation. It does not replace an on-site decision by a designer, installer, contractor, or manufacturer. Fabrication, structure, electrical work, gas, waterproofing, and personal safety require suitably qualified verification.