How much coving do I need for a room?

Measure the room perimeter, subtract any doorway openings, and divide by the coving length. Add 10% for waste from mitre cuts. A standard 4m x 5m room has an 18m perimeter.

How many mitre cuts do I need?

Each internal corner requires 2 mitre cuts (one on each meeting piece). External corners also need 2 cuts. A standard rectangular room with 4 internal corners needs 8 mitre cuts.

What adhesive should I use for coving?

Use a dedicated coving adhesive or grab adhesive. One tube typically covers 3-4 metres of coving. Apply to both the wall and ceiling contact surfaces.

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Cornice & Coving Calculator — Lengths, Adhesive & Mitre Cuts

Calculate cornice and coving lengths, adhesive and mitre cuts for any room. Accounts for doorways and corner types.

Room Perimeter

Total perimeter of the room

Coving Length

Internal Corners

Standard room = 4

External Corners

e.g. chimney breast

Doorways to Skip

No coving above doorways

How We Calculate This

This calculator works out the coving lengths needed by subtracting doorway widths from the room perimeter, then dividing by the coving piece length. Mitre cuts are calculated based on the number of internal and external corners.

The formula

Effective perimeter = Room perimeter - (Doorways × Doorway width)
Lengths needed = Effective perimeter ÷ Coving length

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.