Coving Calculator | Room Perimeter Estimator
Instantly calculate the amount of coving, cornice, or plaster moulding needed for your room in metres and number of pieces, including standard cutting wastage.
Calculate Your Coving Needs
Enter your room dimensions and coving details below to get an instant, accurate estimate of the total metres and number of coving pieces required.
Coving Estimator
Enter your room details to see the estimated material needed
Standard room = 4
e.g., bay windows, pillars
Check the packaging of your chosen coving
10% for simple rooms, 15-20% for complex layouts
Estimated Material
Calculated based on room perimeter and wastage
Coving Material Reference Chart
Standard lengths and typical wastage rates for different types of coving and cornice. Use this to verify your manual calculations or adjust the estimator above.
| Coving Type | Standard Lengths | Recommended Wastage | Best For |
|---|---|---|---|
| Plaster Coving | 2.4m / 3.0m | 10% – 15% | Traditional homes, high-end finishes |
| Polystyrene Coving | 2.0m | 10% | Budget-friendly, lightweight DIY projects |
| Polyurethane Coving | 2.4m / 3.0m | 10% – 12% | Durable, moisture-resistant areas (e.g., kitchens) |
| Complex Room Layouts | Any | 15% – 20% | Rooms with bay windows, alcoves, or many corners |
Coving Calculator FAQ
Everything you need to know about calculating coving and cornice requirements for your decorating project.
Measure the length and width of your room to find the perimeter: (Length + Width) × 2. Add 10% to 15% for cutting wastage, then divide this total by the length of the coving pieces you are buying (e.g., 2.4m) to find the total number of pieces needed.
It is standard practice to allow 10% to 15% wastage for coving. Simple rectangular rooms may only need 10%, while complex rooms with many internal or external corners, chimney breasts, or diagonal cuts may require up to 20% wastage.
Internal corners are where two walls meet to form a concave angle (like a standard room corner). External corners are where walls meet to form a convex angle (like a bay window or chimney breast). External corners often require more careful cutting and can increase material wastage.
In the UK, the most common standard lengths for plaster and polystyrene coving are 2.4 metres and 2.0 metres. Longer 3.0 metre lengths are also available and are useful for larger rooms to reduce the number of visible joints.