Ceiling Paint Calculator — How Much Ceiling Paint Do I Need?

Our ceiling paint calculator works by multiplying room length by width to get the ceiling area, then dividing by the coverage rate for your ceiling type. For new plaster ceilings, it separately calculates the mist coat (diluted emulsion) and the top coats, as they have different coverage rates.

The formula

Ceiling area = Room length × Room width

Top coat litres = (Ceiling area × Number of coats) ÷ Coverage rate × Wastage factor

For new plaster: Mist coat litres = Ceiling area ÷ 8 m²/L × Wastage factor (applied as 1 coat)

For example, a 4m × 3.5m ceiling (14 m²) with smooth plaster, 2 coats at 12 m²/L: 14 × 2 ÷ 12 = 2.3 L, plus 10% wastage = 2.6 L. You'd need 2 × 2.5L tins.

For new plaster, add a mist coat: 14 ÷ 8 = 1.75 L, plus 10% = 1.9 L. Total = 2.6 + 1.9 = 4.5 L.

Coverage rates by ceiling type

• Smooth Plaster: 12 m²/L — standard previously painted ceiling
• Textured / Artex: 6 m²/L — rough texture absorbs significantly more paint
• New Plaster (mist coat): 8 m²/L — diluted emulsion for sealing
• New Plaster (top coats): 12 m²/L — standard coverage once sealed

These rates are based on Dulux and Crown ceiling paint product data. Actual coverage depends on the ceiling condition and paint application method. Use a roller for best results — a medium-pile roller (9-12mm) for smooth ceilings and a long-pile roller (12-18mm) for textured ceilings.