Paint Calculator UK - Calculate How Much Paint You Need
How Much Paint Do I Need for My Room?
Whether you're refreshing a single room or decorating your entire home, our free UK paint calculator helps you work out exactly how many litres of paint to buy. Simply enter your room dimensions, choose your paint type, and we'll calculate the optimal amount including recommended tin sizes from major UK retailers like B&Q, Wickes, and Screwfix.
Avoid waste and save money by calculating the right amount first time. Our calculator accounts for doors, windows, number of coats, and different surface types.
Room Dimensions
Deductions (Doors & Windows)
Paint Options
UK Paint Tin Sizes Available
Paint in the UK comes in standard tin sizes. Buying larger tins is usually more cost-effective per litre:
Pro Tip: Always buy from the same batch for colour consistency. If buying multiple tins, mix them together in a large bucket ("boxing") before starting to ensure uniform colour across all walls.
UK Paint Brand Coverage Rates
Coverage rates vary significantly between paint brands and quality levels. Premium paints often require fewer coats, making them more economical despite higher price:
| Brand | Type | Coverage (m²/L) | Price Range (5L) |
|---|---|---|---|
| Dulux Trade | Professional emulsion | 16-17 m² | £45-70 |
| Crown Trade | Professional emulsion | 15-16 m² | £40-60 |
| Dulux | Retail emulsion | 12-14 m² | £30-50 |
| Crown | Retail emulsion | 12-14 m² | £25-45 |
| Farrow & Ball | Designer estate emulsion | 10-12 m² | £50-60 (2.5L) |
| Little Greene | Designer emulsion | 10-12 m² | £45-55 (2.5L) |
| Johnstone's | Trade/retail emulsion | 12-14 m² | £20-35 |
| Wickes/B&Q Own Brand | Budget emulsion | 8-10 m² | £15-25 |
Types of Paint Finish Explained
Choosing the right finish affects both appearance and durability. Here's what each finish means in the UK market:
Matt / Flat
No sheen, absorbs light. Best for ceilings and living areas. Hides imperfections but marks easily.
Best for: Ceilings, bedrooms, living rooms
Silk / Satin
Subtle sheen, wipeable surface. More durable than matt, shows imperfections more.
Best for: Hallways, kitchens, bathrooms, children's rooms
Eggshell
Very slight sheen, extremely durable. Popular for woodwork in period properties.
Best for: Doors, skirting boards, woodwork
Gloss
High shine, very durable and wipeable. Traditional finish for woodwork.
Best for: Front doors, radiators, exterior woodwork
Dead Flat
Ultra-matt, chalky appearance. Premium decorative finish, marks very easily.
Best for: Feature walls, period properties, low-traffic areas
Kitchen & Bathroom
Moisture-resistant, anti-mould formula. Wipeable with slight sheen.
Best for: Kitchens, bathrooms, utility rooms
Average UK Room Paint Requirements
Here are typical paint quantities for common UK room sizes (based on 2.4m ceiling height, 2 coats, standard doors and windows deducted):
Small Bedroom
Size: 3m × 2.5m
Wall Area: ~26m²
Paint Needed: 5L (2 coats)
Plus Ceiling: +7.5m² (add 1.5L)
Double Bedroom
Size: 4m × 3.5m
Wall Area: ~36m²
Paint Needed: 6-7L (2 coats)
Plus Ceiling: +14m² (add 2.5L)
Living Room
Size: 5m × 4m
Wall Area: ~43m²
Paint Needed: 8L (2 coats)
Plus Ceiling: +20m² (add 3.5L)
Bathroom
Size: 2.5m × 2m
Wall Area: ~22m²
Paint Needed: 4L (2 coats)
Use specialist bathroom paint
Kitchen
Size: 3.5m × 3m
Wall Area: ~31m² (less for units)
Paint Needed: 5-6L (2 coats)
Use specialist kitchen paint
Hallway
Size: 4m × 1.2m
Wall Area: ~25m²
Paint Needed: 5L (2 coats)
Consider durable silk finish
Essential Wall Preparation Before Painting
Proper preparation is crucial for a professional finish. Skipping these steps often leads to paint failure, peeling, or poor coverage:
Step-by-Step Preparation:
- Clear the room - Remove furniture or cover with dust sheets. Take down curtains, pictures, and light fittings where possible.
- Clean walls with sugar soap - Mix sugar soap with warm water (follow packet instructions). Wash walls thoroughly to remove grease, smoke residue, and dirt. Rinse with clean water.
- Fill holes and cracks - Use Polyfilla or similar for small holes. For larger holes, use a bonding coat filler. Deep cracks may need cutting out and filling in layers.
- Sand when dry - Once filler is completely dry, sand smooth with 120-grit sandpaper. Wipe away dust with a damp cloth.
- Apply primer where needed - New plaster needs a mist coat (watered-down emulsion). Stained areas need stain blocker. Bare wood needs primer/undercoat.
- Mask edges - Use quality masking tape (Frog Tape or similar) around windows, doors, skirting boards. Press edges firmly to prevent bleed.
- Lightly sand glossy surfaces - Previously glossed areas need light sanding to provide a key for new paint.
New Plaster
Wait 4-6 weeks for plaster to dry. Apply mist coat (emulsion diluted 10-20% with water) first, then 2 full coats.
Problem Areas
Water stains, nicotine, or marker pen need stain-blocking primer (Zinsser BIN or similar) before painting.
Colour Changes
Going from dark to light? Apply grey primer first to reduce the number of topcoats needed.
Professional Decorating Tips
Order of Painting
Always paint in this order: ceiling first, then walls, then woodwork (doors, skirting, window frames). This allows you to cut in precisely and cover any drips.
Boxing Your Paint
If using multiple tins, pour them all into a large bucket and mix thoroughly. This ensures consistent colour across all walls - batch variations can be noticeable.
Cutting In Technique
Use a 2-inch angled brush to paint corners and edges first. Work in sections, keeping a wet edge to blend with roller work.
Roller Selection
Short pile (5mm) for smooth walls, medium pile (9mm) for slight texture, long pile (12mm+) for textured surfaces like Artex. Use quality rollers to avoid shedding.
Drying Between Coats
Wait minimum 2-4 hours between coats (check tin). Apply second coat at right angles to first for even coverage. Don't rush - paint that isn't dry will lift.
Temperature Matters
Paint between 10-25°C. Cold paint applies poorly and takes ages to dry. Too hot and it dries before you can spread it properly. Avoid direct sunlight.
Woodwork Paint Requirements
Planning to paint doors, skirting boards, or window frames? Here are typical coverage requirements:
| Item | Typical Area | Paint Needed (2 coats) | Recommended Finish |
|---|---|---|---|
| Standard internal door (both sides) | 4m² | 500ml | Eggshell or Satinwood |
| Door frame (architrave) | 1m² | 150ml | Eggshell or Satinwood |
| Skirting board (per room avg) | 3-4m² | 400ml | Eggshell or Gloss |
| Standard window frame | 1.5m² | 200ml | Gloss (exterior grade) |
| Standard radiator | 2m² | 300ml | Radiator enamel |
| Banister/spindles (per floor) | 4-6m² | 500-750ml | Eggshell or Satinwood |
Woodwork Note: Always use undercoat/primer on bare wood. For previously gloss-painted surfaces, lightly sand, clean with sugar soap, then apply new topcoat. Water-based satinwood is easier to work with than traditional oil-based gloss.
Frequently Asked Questions About Paint Calculations
To calculate paint needed: 1) Measure total wall area (height × perimeter), 2) Subtract 10% for windows and doors, 3) Divide by coverage rate (typically 10-12m² per litre for emulsion), 4) Multiply by number of coats (usually 2). For a standard UK room with 2.4m ceiling height and 4m × 3m floor space, expect approximately 5-6 litres for walls with two coats.
Quick formula: Wall area = Height × (2 × Length + 2 × Width) - Door/window areas
UK paint coverage varies by brand and type:
- Dulux Trade emulsion: 16-17m²/L
- Dulux retail: 12-14m²/L
- Crown paints: 12-14m²/L
- Farrow & Ball: 10-12m²/L (high pigment load)
- Little Greene: 10-12m²/L
- Budget paints: 8-10m²/L
Always check the tin label for specific coverage rates as these can vary between product lines.
Yes, you should deduct window and door areas from your wall calculations:
- Standard UK door: 2m² (1.98m × 0.76m)
- Standard window: 1.5m²
- Patio door: 3m²
For a typical room with one door and one window, deduct approximately 3.5m². However, many professional decorators recommend buying 10% extra paint anyway for touch-ups, cutting in properly, and ensuring good coverage on edges and corners.
UK paint tin sizes are standardised:
- Tester pots (75ml-100ml): For colour sampling, covers ~0.5m²
- Small tins (1L): For small areas or touch-ups
- Medium tins (2.5L): Most popular for single rooms
- Large tins (5L): Best value per litre for larger projects
- Trade tins (10L): For professionals or whole-house projects
For best value, buy the largest size practical for your project as price per litre decreases significantly with tin size.
Number of coats depends on several factors:
- New plaster: Mist coat (diluted) plus 2 full coats
- Repainting similar colour: 2 coats standard
- Dramatic colour change: 3+ coats (or use grey primer first)
- Dark to light: Primer plus 2-3 coats
- Ceilings: 2 coats typically
Quality paints with high opacity (like Dulux Trade) may achieve full coverage in fewer coats, potentially saving money despite higher initial cost.
UK paint finishes explained:
- Matt (flat): No sheen, hides imperfections, ideal for ceilings and low-traffic areas. Marks easily but touch-ups blend well.
- Silk (satin): Subtle sheen, wipeable surface, good for hallways, kitchens, bathrooms and children's rooms.
- Eggshell: Slight sheen, very durable, popular for woodwork and period properties.
- Gloss: High shine, extremely durable, traditional for doors and skirting boards.
- Dead flat: Ultra-matt premium finish, chalky appearance, very delicate.
Sheen level affects both coverage rates and durability. Higher sheen = more durable but shows imperfections more.
UK paint prices (2025):
- Budget range (Johnstone's, own brands): £15-25 per 5L
- Mid-range (Dulux, Crown): £30-50 per 5L
- Premium trade (Dulux Trade, Crown Trade): £45-70 per 5L
- Designer (Farrow & Ball, Little Greene): £50-60 per 2.5L
Trade paints offer better coverage and durability, often making them more cost-effective despite higher upfront cost. A quality trade paint may need 2 coats where budget paint needs 3.
Proper wall preparation steps:
- Clean walls with sugar soap to remove grease and dirt
- Fill holes and cracks with appropriate filler (Polyfilla for small, bonding for large)
- Sand filled areas smooth when completely dry
- Apply primer/sealer on bare plaster, stains, or problem areas
- Lightly sand glossy surfaces for adhesion
- Mask edges with quality masking tape
Good preparation ensures better coverage, longer-lasting results, and a more professional finish. Rushing preparation is the most common DIY decorating mistake.
Where to Buy Paint in the UK
Compare prices across major UK retailers for the best deals:
B&Q
Wide range, own brand "Colours" plus major brands. Good for Dulux and Crown.
Wickes
Competitive trade prices, own brand plus Dulux Trade range.
Screwfix
Trade-focused, excellent for Dulux Trade and professional supplies.
Homebase
Good colour mixing service, range of premium and budget options.
Amazon
Often discounted prices, especially for larger tins. Check reviews carefully.
Dulux Decorator Centres
Trade prices, expert colour advice, professional quality paints.
Money-saving tip: Sign up for trade accounts at B&Q, Wickes, or Screwfix for discounts even if you're a DIYer. Look for bank holiday sales and end-of-line colours for significant savings.
Pro Tips for Accurate Results
- Double-check your input values before calculating
- Use the correct unit format (metric or imperial)
- For complex calculations, break them into smaller steps
- Bookmark this page for quick future access
Understanding Your Results
Our Paint Calculator provides:
- Instant calculations - Results appear immediately
- Accurate formulas - Based on official UK standards
- Clear explanations - Understand how results are derived
- 2025/26 updated - Using current rates and regulations
Common Questions
Is this calculator free?
Yes, all our calculators are 100% free to use with no registration required.
Are the results accurate?
Our calculators use verified formulas and are regularly updated for accuracy.
Can I use this on mobile?
Yes, all calculators are fully responsive and work on any device.