Coving Calculator
Enter your room dimensions and get the exact linear metres, number of 2m and 3m lengths, adhesive quantity and a cost estimate. Works for any room shape. 2026 UK pricing.
Fitting Guide
How to measure, choose and fit coving
A practical guide for DIYers, covering measurement, size selection, cutting corners and adhesive application.
How to measure a room for coving
Coving runs along every wall-ceiling junction in the room, so you need the total perimeter. For a rectangular room, add all four wall lengths: perimeter = 2 × (length + width). For an L-shaped or irregular room, measure every wall individually and add them together.
Add 10% wastage to allow for mitre cuts, breakages and off-cuts at corners. For a room with a chimney breast or alcoves creating lots of corners, add 15%. Use the calculator above for the exact count of 2m and 3m lengths.
Choosing the right profile and material
The three most common materials are expanded polystyrene (EPS), polyurethane (PU) and gypsum plaster. EPS and PU are the standard DIY choice — lightweight, easy to cut with a mitre box and installed with adhesive alone. Plaster coving is denser and more durable but significantly heavier; it needs temporary support (nails or props) while the adhesive sets.
For period properties (Victorian, Edwardian, Georgian), a decorative plaster cornice with stepped or ornate profiles will look more proportional than a plain cove. Use the size guide in the table above as a starting point, then assess visually once you've ordered a sample length.
Cutting internal and external corners
Corners are the most difficult part of fitting coving. Each internal corner requires two pieces mitred at 45°. The critical thing most beginners miss is how to hold the coving in the mitre box — the coving must be held at the same angle it will sit on the wall and ceiling, not flat. Most mitre boxes designed for coving have a built-in stop for this.
External corners (e.g. on a chimney breast) are cut the same way but in the opposite direction. Mark pencil lines on the wall and ceiling first so you can see exactly where the coving edges will sit — this makes positioning much easier.
Applying adhesive and holding while it sets
Apply coving adhesive as a thin, continuous bead along both the wall face and the ceiling face of the coving back. Press the coving firmly into position, sliding it slightly as you push to help the adhesive key in. Hold for 30–60 seconds, then use strips of masking tape across the face of the coving — angled down to the wall and up to the ceiling — to support it while the adhesive sets (typically 20–40 minutes).
Once all lengths are fitted, fill any corner gaps and nail holes with a fine surface filler. Sand smooth when dry, wipe off dust and apply a single coat of mist coat emulsion (50:50 diluted) before finishing with full-strength paint.
2m vs 3m lengths — which should you order?
Longer lengths mean fewer joins in the finished result, which is almost always better-looking. 3m lengths are the trade standard and are more economical per linear metre. The trade-offs are handling (harder to manoeuvre alone in a small space) and transport (you need a large vehicle or delivery).
For a typical UK living room, 3m lengths will give you 6–7 joins around the room instead of 9–10. In a hallway where lengths often run full-wall without a join anyway, the difference is less significant. The calculator above shows both options so you can decide based on your situation.
FAQs
Coving questions answered
Measure the perimeter of the room (add all four wall lengths together), then add 10% for wastage on cuts and corners. A standard 5×4m room has an 18m perimeter — you need approximately 20 linear metres including wastage. Use the calculator above to get your exact figure for any room size.
Match coving size to ceiling height. Standard rooms with 2.1–2.4m ceilings suit 90–100mm coving. Rooms with 2.4–2.7m ceilings suit 100–127mm. Ceilings over 2.7m look best with 127mm or a decorative plaster cornice. Using coving that is too small in a tall room looks lost; too large in a low room looks heavy and can make the ceiling feel oppressive.
Allow approximately 1kg of coving adhesive per 5 linear metres. A standard 1kg tub covers around 4–6m depending on how generously you apply it. For a 20m room, order 4 × 1kg tubs or 1 × 5kg tub. Always have one spare — running out before the adhesive goes off is a common and frustrating mistake.
3m lengths give fewer joins and a neater result. They are also more economical per linear metre. The trade-offs are that they are harder to handle alone in a small room and harder to transport without a large vehicle. 2m lengths are easier for a solo DIYer. Whichever you choose, the total linear metres needed stays the same — only the number of lengths and joins differs. The calculator above shows both options so you can compare directly.
Internal corners are cut at 45° in a mitre box, with the coving held at the angle it sits on the wall and ceiling — not flat. The two pieces meet to form a right angle. External corners (e.g. on a chimney breast) are cut in the opposite direction. Mark pencil lines on the wall and ceiling first so you can see exactly where the coving will sit before cutting. Cut, test-fit and adjust each corner before moving on — walls are rarely perfectly square.
Both run along the wall-ceiling junction. Coving is a plain concave or simple ogee profile — typically lightweight polystyrene, polyurethane or plaster. Cornice is a more ornate decorative moulding, traditionally solid plaster, with stepped profiles, dentils or egg-and-dart detail. Cornice is heavier, more expensive and typically used in period properties. Coving is the standard choice for modern homes and DIY fitting.
Yes — lightweight polystyrene and polyurethane coving is very DIY-friendly. It is light enough to hold in place while you apply adhesive, forgiving of small corner gaps that can be filled, and easy to cut with a standard mitre box and fine-tooth saw. Plaster coving is more challenging — it is heavier and needs temporary support (props or masking tape) while the adhesive sets. Start with a small room to practise mitre cuts before tackling the whole house.
Yes, in almost all cases. Fitting over old coving gives a messy finish, makes mitre cuts at corners unreliable and risks the old coving pulling away from the wall and taking the new with it. Remove old coving, fill and sand any surface damage, then prime any bare plaster before fitting new. If the existing coving is solid plaster and bonded hard to the surface, seek a plasterer's advice before removal — it may be more trouble than it is worth to remove.
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