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Walls + Ceiling
🎨 Paint Calculator
Enter room length, width, and ceiling height to instantly calculate paint litres for walls and ceiling - with automatic door and window deductions. Set your paint coverage rate, number of coats, and tin size to see exactly how many tins to buy and the total cost. Add multiple rooms for a whole-house estimate.
🎨 Paint Calculator
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Total Paint Needed
🏠 Room-by-Room Calculator
Add each room individually for a whole-house estimate.
📐 Paint Calculation Guide
Basic Formula
Net Paintable Area = Total Wall Area
- Door Area (2.0 × 0.9 = 1.8 m² each)
- Window Area (1.2 × 1.0 = 1.2 m² each)
Paint Needed (L) = Net Area × No. of Coats
/ Coverage per Litre
Tins to Buy = Ceil(Paint Needed / Tin Size)
Example: 4m × 3.5m room, 2.8m ceiling, 1 door, 2 windows
Wall area = (4+3.5+4+3.5) × 2.8 = 42 m²
Ceiling = 4 × 3.5 = 14 m²
Deduct = 1×1.8 + 2×1.2 = 4.2 m²
Net area = (42 + 14) − 4.2 = 51.8 m²
2 coats, 14 m²/L:
Paint = 51.8 × 2 / 14 = 7.4 L
Tins = 2 × 4L tins
Standard Coverage Rates (Litres per m²)
Economy emulsion: 12–13 m²/L
Standard emulsion: 14–16 m²/L
Premium emulsion: 16–18 m²/L
Exterior emulsion: 10–12 m²/L
Texture paint: 8–10 m²/L
Masonry paint: 7–10 m²/L
Primer / undercoat: 10–12 m²/L
Gloss / enamel (metal): 14–16 m²/L
Wood paint: 12–14 m²/L
Note: Coverage reduces on rough/porous surfaces.
Always buy 10% extra for wastage and touch-ups.
When to Use Primer?
New plaster / bare walls: Always use primer
Changing from dark to light: Use white primer
Previously painted (good): Usually skip primer
Stained/water-marked walls: Stain-block primer
Old chalky/flaking paint: Sand + seal first
Primer typically reduces final coats needed
from 3 to 2, saving overall paint cost.
❓ Frequently Asked Questions
AI Painting Advisor - Coming Soon!
AI-powered paint quantity estimation, brand recommendations and colour scheme suggestions based on room size and lighting.
⏳ Coming Soon - Stay Tuned!
Paint Calculator - How to Calculate Paint for Any Room or House
Buying too much paint wastes money. Buying too little means a mid-project trip back to the hardware store, and a risk that the new batch is a slightly different shade. Accurate paint estimation takes three minutes with this calculator - far less time than guessing and dealing with the consequences.
Step-by-step example: Living room 5m × 4m, 2.7m ceiling height, 2 doors (1.8 m² each), 2 windows (1.2 m² each), 2 coats of standard interior emulsion (12 m²/L coverage). Wall area = (5+4)×2 × 2.7 = 48.6 m². Deduct 4 openings: 48.6 − 6.0 = 42.6 m². Paint needed = 42.6 ÷ 12 × 2 = 7.1 litres. Buy two 4L tins or one 8L tin.
Paint Coverage Rates - What to Expect by Paint Type
Interior Paint Coverage
- Economy/budget emulsion: 10–12 m²/L. Lower pigment load, often thinner consistency.
- Standard interior emulsion: 12–15 m²/L. The most common type for walls and ceilings.
- Premium interior paint: 14–18 m²/L. Higher pigment density, better one-coat coverage.
- Flat/matte finish: Hides imperfections well; typically 12–14 m²/L.
- Satin/semi-gloss: More durable, washable; slightly lower coverage 10–13 m²/L.
Exterior & Specialty Coverage
- Exterior/masonry paint: 8–12 m²/L. Higher pigment for opacity and UV resistance.
- Primer/undercoat: 10–12 m²/L. Applied before finish coats on new surfaces.
- Textured/rendered surfaces: 6–9 m²/L. Porous surface absorbs significantly more.
- Gloss paint (doors, trim): 12–14 m²/L for brushed application.
- Always check the specific coverage stated on the manufacturer's tin - it varies by product.
How Many Coats Do You Need?
- Repainting same or similar colour (good existing surface): 1–2 coats. If the existing paint is sound and the colour change is subtle, 1 coat of premium paint may suffice.
- Changing from dark to light colour: 2–3 coats, or prime first with white tinted primer to reduce the number of finish coats needed.
- New plaster or bare drywall: 1 coat diluted primer (10–20% water) to seal the porous surface, then 2 coats of finish. Skipping the primer on new plaster leads to uneven absorption and patchy results.
- Deep, rich, or dark colours: 2–3 coats - pigment-heavy colours often have lower opacity per coat.
Interior vs Exterior Paint - Key Differences
These are not interchangeable products despite looking similar:
- Interior paint is formulated for low VOC, easy cleaning, and colour consistency in controlled environments. It will fade, crack, and peel when exposed to UV, moisture, and temperature variation outdoors - sometimes within a few months.
- Exterior paint contains fungicide (prevents mould and mildew growth), UV stabilisers (prevents fading), and flexible binders that accommodate thermal expansion and contraction. Never substitute interior paint for exterior applications.
- Coverage: Exterior paint typically covers 8–12 m²/L vs 12–15 m²/L for interior - it has a heavier pigment load needed for durability and opacity in outdoor conditions.
- Application: Exterior paint should be applied in dry weather above 10°C and allowed to cure fully (typically 2–4 weeks) before exposure to rain or extreme temperatures.