Painting Calculator UK | How Much Paint Do I Need?
Free UK painting calculator. Work out how many litres of paint you need for walls, ceilings and woodwork. Covers emulsion, gloss, primer and masonry paint.
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Results are estimates only and may vary depending on site conditions, material specifications and waste. EasyEstimate and its affiliates accept no responsibility for any loss or damage arising from reliance on these figures. Always verify quantities with your supplier before ordering.
How to Calculate Paint Quantities
Running out of paint mid-job or having 10 leftover tins are both avoidable with simple maths. This guide shows you how to work out exactly how much paint you need for any room or exterior in the UK.
The Formula
- Wall area = Perimeter (m) × Height (m) − openings (doors/windows)
- Ceiling area = Length × Width
- Litres needed = Area ÷ coverage rate × number of coats
Coverage Rates by Paint Type
| Paint Type | Coverage (m²/litre) | Typical Use |
|---|---|---|
| Matt emulsion | 12–14 | Walls, ceilings (living rooms, bedrooms) |
| Silk emulsion | 12–14 | Walls (kitchens, hallways, bathrooms) |
| Soft sheen emulsion | 12 | High-traffic areas |
| Eggshell (water-based) | 14–16 | Woodwork, trim |
| Gloss (solvent-based) | 16–17 | Woodwork, doors, skirting |
| Satinwood | 16 | Woodwork (modern alternative to gloss) |
| Primer/undercoat | 12–14 | New surfaces, colour changes |
| Masonry paint | 8–10 | External walls |
| Floor paint | 8–10 | Garage floors, workshops |
| Ceiling paint | 12 | Ceilings (thicker formula, less drip) |
Worked Example: Standard UK Room (3m × 4m × 2.4m)
Walls:
- Perimeter = (3 + 4 + 3 + 4) = 14m
- Gross wall area = 14 × 2.4 = 33.6 m²
- Subtract: 1 door (1.6 m²) + 1 window (1.44 m²) = 3.04 m²
- Net wall area = 30.56 m²
- Two coats at 13 m²/litre = 30.56 × 2 ÷ 13 = 4.7 litres → buy 5 litres
Ceiling:
- Ceiling area = 3 × 4 = 12 m²
- Two coats at 12 m²/litre = 12 × 2 ÷ 12 = 2 litres → buy 2.5 litres
Woodwork (skirting + architrave + door):
- Skirting = 14m perimeter × 0.15m height = 2.1 m²
- Door + frame = 2.0 m² (both sides) + 1.5 m² frame = 3.5 m²
- Window frame = 1.0 m²
- Total woodwork = 6.6 m²
- One coat undercoat + two coats gloss at 16 m²/litre = 6.6 × 3 ÷ 16 = 1.2 litres → buy 1 litre undercoat + 1 litre gloss
Tin Size Guide
| Tin Size | Covers (2 coats) | Best For |
|---|---|---|
| 1 litre | 6–7 m² | Woodwork, touch-ups, small areas |
| 2.5 litres | 15–18 m² | Single feature wall, ceiling, small room |
| 5 litres | 30–35 m² | Average room walls |
| 10 litres | 60–70 m² | Multiple rooms, large spaces |
New Plaster (Mist Coat)
New plaster must be sealed with a mist coat before applying standard emulsion:
- Mix cheap matt emulsion with water at 70:30 ratio (70% paint, 30% water)
- Apply one coat and allow to dry fully (24 hours)
- Coverage: approximately 8–10 m²/litre (the plaster absorbs heavily)
- Then apply 2 coats of your chosen emulsion
Exterior Painting
Exterior masonry paint has lower coverage and often needs more coats:
| Surface | Coats Needed | Coverage (m²/litre) |
|---|---|---|
| Previously painted (good condition) | 2 | 10 |
| Previously painted (weathered) | 2–3 | 8 |
| Bare render/pebbledash | 3 | 6–8 |
| New blockwork | 3 | 6 |
Example: 3-bed semi exterior (100 m² wall area, previously painted):
- 100 m² × 2 coats ÷ 10 m²/litre = 20 litres masonry paint
From Paint Quantities to a Full Decoration Estimate
This guide gives you paint volumes. A complete decoration estimate also includes:
- Preparation (filling, sanding, masking, dust sheets)
- Labour (typically £150–200/day for a decorator in 2026)
- Specialist products (sugar soap, filler, caulk, masking tape)
- Access equipment (ladders, scaffold towers for exteriors)
- Wallpaper stripping if needed
EasyEstimate’s decoration calculators handle all of these elements with live UK pricing, so you can produce a complete, priced estimate in minutes.
Try the full painting & decoration calculator free →
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Frequently Asked Questions
- How much paint do I need per square metre?
- Standard emulsion covers approximately 12–14 m² per litre for a single coat on a smooth surface. Two coats on 12 m² wall = 24 m² coverage needed = approximately 2 litres. Textured or porous surfaces need up to 30% more paint.
- How many litres of paint for a room?
- A typical UK room (3m × 4m × 2.4m) has approximately 30 m² of wall area after subtracting a door and window. At 12 m²/litre and two coats, you need about 5 litres of emulsion for the walls plus 1.5 litres for the ceiling.
- What's the difference between matt, silk and eggshell paint?
- Matt has no sheen and hides surface imperfections — ideal for living rooms and bedrooms. Silk has a slight sheen and is wipe-clean — good for kitchens and hallways. Eggshell has a soft sheen and high durability — used for woodwork and trim.
- How much paint do I need for the exterior of a house?
- Measure each wall face (height × width), subtract windows and doors, and total the area. Masonry paint covers 8–10 m²/litre. A typical 3-bed semi has approximately 80–120 m² of external wall area. Allow 3 coats for bare render.
- Do I need primer before painting?
- Primer is needed on new plaster (use mist coat — diluted emulsion), new timber, bare MDF, and when changing from dark to light colours. On previously painted surfaces in good condition, you can apply directly.
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