Carpet Calculator UK — Area, Underlay & Gripper Rod

In the UK, carpet typically comes in two standard roll widths: 4 metres and 5 metres. 4m is the most common width and suits most rooms. If your room is wider than the roll width, a seam (join) will be needed. A good fitter can make seams nearly invisible. Some budget carpets only come in 4m width. For hard-floor alternatives, see our Laminate Flooring Calculator or Vinyl Flooring Calculator.

Split the room into two rectangles and measure each one wall to wall. In the calculator, press Add section and enter each rectangle as its own section: the carpet for every section is worked out separately against the roll width, rounded up to the next 0.1m, then added together, so the total never comes up short. Each section is cut from the roll as its own piece, which means there will be a join where the sections meet; a professional fitter can advise on the most economical cutting layout and where a join is least visible. Gripper rod is estimated from each section's full perimeter, which slightly over-counts at the join, so treat it as a safe upper figure.

Yes, underlay is strongly recommended for fitted carpet. It extends carpet life, improves comfort, reduces noise, and provides insulation. Standard UK underlay rolls are 11m × 1.37m (approximately 15 m²). Choose 8–11mm thickness for living areas and stairs. Cheaper sponge underlay is false economy — crumb rubber or PU foam underlay lasts longer. If you have underfloor heating, ensure the combined carpet and underlay tog rating does not exceed 2.5 — see our Underfloor Heating Coverage Calculator.

Gripper rod (also called carpet grippers or tack strips) are thin wooden strips with angled pins that hold fitted carpet in place around the room edges. You need enough to run around the full perimeter minus doorway openings. Standard UK gripper rod comes in 1.52m (5ft) lengths, so divide your total perimeter metres by 1.52 to estimate the number of rods (1.2m lengths are also sold). For a standard door opening (0.8m), subtract 0.8m from the perimeter for each doorway.

Allow 10% extra for wastage when ordering carpet. Carpet must be cut from a rectangular piece off the roll, so you inevitably lose material at the room edges and in odd-shaped areas. If you have alcoves, bay windows or angled walls, increase this to 15%. It is also worth keeping a small offcut for future repairs. After laying carpet, fit skirting boards — use our Skirting Board Calculator for quantities.

Measure the longest and widest points of the room, wall to wall, in metres. Measure into every doorway up to the point where the carpet will stop (usually under the centre of the closed door), and measure any alcoves, bay windows, chimney breasts or recesses separately. In older UK homes walls are rarely perfectly square, so take the measurement at a few points and always use the largest figure. Enter the longest dimension as the length and the widest as the width above, then leave the wastage allowance on so the calculator adds carpet for trimming. If in any doubt, a professional fitter measuring on site is the safest way to avoid ordering short.

Carpet prices vary widely by type and quality, so there is no single fixed UK rate — budget polypropylene carpets typically start at the lower end per m², while wool and wool-blend carpets cost considerably more, and that is before underlay, gripper rod, door bars and fitting. Because prices change constantly, enter your own supplier's price per m² in the optional price field above to get a cost estimate based on the actual carpet area you need to buy. Remember the calculator prices the carpet area cut from the roll (which can be larger than the room's floor area), not just the room m², so your estimate reflects what you will actually pay for.

UK carpet is now sold and priced in square metres (m²), but some older retailers still quote in square yards, which can make a like-for-like price comparison confusing. One square yard equals 0.8361 m² (and one square metre is about 1.196 square yards), so a price quoted per square yard looks roughly 16% cheaper (about a sixth less) than the same carpet quoted per square metre — even though it is the same carpet. Always convert quotes to the same unit before comparing. This calculator works entirely in metres and reports the carpet area in m², matching how UK carpet is sold today.

This calculator is designed for rectangular rooms, not stairs, but a reliable rule of thumb for a straight UK staircase is to add the tread depth (the flat part you step on) and the riser height (the vertical part) for one step, add about 5cm for fitting and wrapping, then multiply by the number of steps to get the total carpet length you run up the stairs. Multiply that length by the stair width to get the area, and add the landing separately. Winder (curved) steps must be measured individually at their widest point because they use more carpet, and the top riser is normally part of the landing carpet. Stairs need extra material, so add at least 10% wastage and ask your fitter to confirm before ordering.