How do I calculate coving for a room?

Measure the room perimeter (2 × length + 2 × width) and divide by the coving piece length (typically 2m or 3m). Add 10% wastage for mitre cuts and off-cuts. For example, a 3.5m × 4m room has a 15m perimeter, requiring 5 pieces of 3m coving, or about 6 pieces with wastage.

How much coving adhesive do I need?

One standard 310ml cartridge of coving adhesive typically covers 4-5 pieces of coving. So for a room needing 8 pieces of coving, you would need 2 cartridges. Popular brands include Gyproc Cove Adhesive and No More Nails. Always have a spare tube on hand.

How do I cut coving mitre joints?

Use a mitre box or coving mitre template for accurate 45-degree cuts. For internal corners, cut the coving with the ceiling edge flat in the mitre box. For external corners, reverse the cut direction. Many plasterers prefer using a coving template (available from Screwfix and B&Q) which makes cutting much easier and more accurate.

What size coving should I choose?

For standard UK rooms with 2.4m ceilings, 100-127mm (4-5 inch) coving is the most popular. Larger rooms with higher ceilings suit 150mm+ coving. Most polystyrene and plaster coving comes in 2m or 3m lengths. 3m lengths are better value and create fewer joints but are harder to handle solo.

What types of coving are available?

The main types in the UK are: plaster coving (traditional, heavy, requires adhesive), polystyrene coving (lightweight, cheap, easy to fit), polyurethane coving (durable, lightweight, good detail), and Duropolymer coving (moisture-resistant, for bathrooms). Gyproc plaster coving is the standard trade choice. If you are also boarding the room, use our Plasterboard Calculator to estimate sheet quantities.

Coving Calculator — How Many Pieces of Coving for a Room?

Coving Calculator — Pieces, Adhesive & Mitre Cuts

Calculate how many coving pieces, adhesive tubes, and mitre cuts you need for any room. Based on standard UK coving lengths.

Room Length

Room Width

Internal Corners

Standard rectangular room has 4

External Corners

e.g. chimney breast or bay window

Coving Length Per Piece

3m is standard trade length

Include wastage allowance

Adds 10% extra for mitre cuts and breakage

Wastage Percentage

10% is standard for coving

Price Per Coving Piece (optional)

Price per coving length

Price Per Adhesive Tube (optional)

Price per 310ml cartridge

How We Calculate This

Our coving calculator works by computing the room perimeter and dividing by your chosen coving piece length. We also calculate the adhesive needed and count the mitre cuts required for each corner.

The formula

Perimeter = 2 × (Room length + Room width)

Pieces needed = Perimeter ÷ Piece length × Wastage factor

Adhesive tubes = Total pieces ÷ 4 (1 tube per 4 pieces)

Mitre cuts

Each corner — whether internal or external — requires 2 mitre cuts (one on each piece of coving that meets at the corner). A standard rectangular room with 4 internal corners needs 8 mitre cuts. External corners (on chimney breasts, bay windows, etc.) also need 2 cuts each.

Standard UK sizes

2m lengths: Easier to handle but more joints
3m lengths: Fewer joints, better value, standard trade choice

The 10% wastage allowance covers mitre cut waste, breakage, and off-cuts that are too short to use. Coving is relatively fragile, so having a spare piece is always recommended.

Frequently Asked Questions

Last updated: February 2026

All calculations are estimates. Verify with your supplier.

Coving Calculator — Pieces, Adhesive & Mitre Cuts

How We Calculate This

The formula

Mitre cuts

Standard UK sizes

Frequently Asked Questions

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