Paint Calculator

Painting Guide

What do I need to know about Paint Coverage Rates?

Coverage varies significantly by paint type and surface. Standard emulsion (vinyl matt, silk): 10–14 m² per litre. Premium emulsion (Farrow & Ball, Little Greene): 10–12 m² per litre. Masonry paint: 5–8 m² per litre. Gloss or satin (woodwork): 14–18 m² per litre. Always check the tin — the stated coverage assumes smooth, sealed surfaces. New plaster, rough or porous surfaces, and highly absorbent substrates will reduce coverage by 30–50%. Use a good primer coat on new plaster and first-time painted surfaces, since it seals the surface and reduces how much of the finish coat gets absorbed — skipping the primer on new plaster can mean needing an extra full coat of the more expensive finish paint to achieve even coverage.

How Many Coats?

One coat: only suitable for touch-ups, re-painting the exact same colour, or if using a paint-and-primer combination on a well-prepared surface. Two coats: standard for most painting projects — gives even coverage and better depth of colour. Three coats: needed for dark colours over light (especially with deep colours like red, dark blue, and black which have poor opacity), new plaster (one coat to seal plus two finish coats), and highly absorbent surfaces. Using cheap paint and applying three coats rarely matches the result of two coats of a quality paint with good pigment density — spend on the paint before spending on extra coats. Always allow the recommended drying time between coats (check the tin; typically 2-4 hours for emulsion, longer for oil-based products) so each layer cures properly rather than lifting the one beneath it.

What do I need to know about Preparation is the Work?

Professional decorators spend 60–70% of their time on preparation — filling, sanding, cleaning, taping. The most common DIY painting failure is inadequate prep. Fill all holes and cracks with Polyfilla, sand smooth when dry, and prime the filled areas. Wash walls with sugar soap to remove grease, nicotine, and general grime — paint will not adhere properly to dirty surfaces. Sand gloss woodwork with 120-grit before repainting — gloss needs a key to accept new paint. Tape edges with low-tack painter's tape rather than standard masking tape, which can pull off fresh plaster or lift previous paint layers when removed. Press the tape down firmly along its edge with a scraper or old card to stop paint bleeding underneath, and remove it while the final coat is still slightly tacky for the cleanest line.

What do I need to know about Paint Finishes for Different Surfaces?

Matt: ceilings and walls in low-traffic areas — hides imperfections well but not washable. Eggshell or washable matt: the modern compromise — looks close to matt but can be wiped clean. Suitable for most walls. Silk: more sheen, highly washable, shows wall imperfections more. Good for kitchens, bathrooms, hallways. Soft sheen: between eggshell and silk. Satinwood: for woodwork (doors, skirting, window frames). Gloss: traditional high-sheen woodwork finish. Water-based (acrylic) paints have largely replaced oil-based (solvent) paints for woodwork in recent years — they dry faster, have far less odour, don't yellow over time, and are easier to clean up, though traditionalists still favour oil-based eggshell for a slightly harder, more durable finish on high-traffic woodwork like skirting and door frames.