Paint
Feature wall and main colour quantities
- where
- feature wall area (m²)
- feature wall length (m)
- wall height (m)
- openings in the feature wall (m²)
- other walls area (m²)
- room length (m)
- room width (m)
- openings in the other walls (m²)
- feature colour (L)
- number of coats
- spreading rate (m²/L)
- main colour (L)
Explain this equation
Splits a room's walls into a feature wall and the rest, and works out each colour separately.
The feature wall is its length times the height, less any openings in it. The other walls are the full perimeter times height, less the feature wall and their own openings. Each area times coats divided by spreading rate gives litres.
Coverage arithmetic: litres equal area times coats divided by spreading rate.
Sense check: a 4 × 3.5 m room with a 4 m feature wall at 2.4 m high gives 9.6 m² of feature and about 22.9 m² of main colour after 3.5 m² of openings.
Watch out: strong feature colours often need an extra coat; set N accordingly.
Splits a room into one feature wall and the rest, and works out the paint for each colour.
Enter your values to see the result.
Good to know
Strong or deep feature colours often need an extra coat or a tinted undercoat to reach full opacity, so increase N for the feature wall if needed and run it again. Spreading rates are from the paint’s data sheet (e.g. 14 m²/L for Farrow & Ball Estate Emulsion, up to 17 m²/L for trade vinyl matts).
Common mistake
Buying the feature colour in the same tin size as the main colour: a single wall often needs only 1–2.5 L.
Limits
Rectangular room with the feature wall as one full wall.
Sources
- Farrow & Ball, How much paint do I need? (coverage per tin, e.g. Estate Emulsion 70 m² per 5 L; Masonry & Plaster Stabilising Primer 100 m² per 5 L; one primer & undercoat plus two topcoats)
- Dulux Trade Vinyl Matt product data sheet (up to 17 m²/L; 2 full coats; seal new or bare surfaces with up to 1 part water to 5 parts paint; packs 1, 2.5, 5 and 10 L)
- Geometry: rectangle and cylinder surface areas, prism volumes
Results are calculations from the published methods and figures shown, and depend on the data you enter. Coverage depends on the product, surface and application. Always follow the paint and wallcovering manufacturers’ data sheets and BS 6150 / BS 8000-12. Check prices and VAT with your own records and HMRC.