Paint calculator
Calculate litres of paint for walls and ceilings based on area and coverage.
Paint calculator
Calculate how much paint you need for walls or ceiling based on dimensions, number of coats and paint coverage.
Room length
Room width
Ceiling height
Typically 6–10 m²/litre depending on paint type and surface
Allowance for uneven surface, extra consumption and safety
Your painting project
11.7 L paint → 2 buckets (10 L) for 42.5 m² walls
Area
42.5 m²
Coats
2
Litres of paint
11.7 L
Buckets
2
Materials
2 coats on 42.5 m² walls (coverage 8 m²/L)
Buy 2 buckets of 10 L = 20 L (surplus 8.3 L)
ℹThe result is an estimate based on dimensions, number of coats, coverage and waste.
ℹRough walls, strong colour changes and porous surfaces can increase consumption.
Example: Living room with 35 m² walls
If a room has a total wall area of about 35 m² and you apply 2 coats with a paint covering 8 m²/litre, you need about 9–10 litres of paint plus a small safety margin.
Calculation for a 5 × 3.5 m living room with 2.5 m ceiling height:
The calculator does not deduct windows and doors — the total provides a good safety margin.
How to calculate paint
Number of coats matters
Most painting projects need 2 coats for even coverage. A single coat is rarely enough, especially when changing colours. For strong colour changes (e.g. dark to light) 3 coats may be necessary. Each coat doubles/triples your litre consumption.
Coverage varies
Coverage (m² per litre) depends on the paint type and surface. Smooth walls with latex typically give 8–10 m²/L, while rough plaster or untreated drywall may need 5–7 m²/L. Always check the paint label for stated coverage.
Always add waste
Even with careful painting some is always lost — in the roller, on edges, in repairs and mixing. 10 % extra is a good starting point. For very rough walls or many corners 15 % may be more realistic.
Walls vs. ceiling
Wall area is calculated as the perimeter × height: 2 × (length + width) × height. Ceiling area is simply length × width. Ceilings often need slightly more paint because painting overhead increases consumption.
How to use this calculator
Four quick steps – you don't need to be a tradesperson to follow them.
- Measure the room's length and height – the calculator works out the wall or ceiling area.
- Enter the number of coats (usually 2 for fresh paint, 1 for a refresh).
- Add the paint coverage (m² per litre) – it's on the tin, typically 8–12 m²/L.
- Check the litres and round up – paint comes in fixed-size tins (2.5 L, 5 L).
Common mistakes
Small things that often cost an extra trip to the hardware store.
- Not subtracting doors and windows – you'll buy more than needed (but a bit extra is rarely wasted).
- Trusting the coverage on the tin without thinking about porous or rough walls.
- Doing one coat of light paint over dark – it almost never covers.
- Skipping primer on new or patched walls.
Example: a 4 × 5 m living room, 2.4 m ceiling
Wall area: about 43 m² (with doors and windows still counted). With 2 coats and 10 m²/L coverage you'll need around 8.6 L. That's either two 5 L tins or one 5 L plus one 2.5 L – always round up.
Frequently asked questions
Short answers to the questions we hear most often about this calculator.
How much does 1 litre of paint cover?
Usually 8–12 m² per coat on a smooth surface. Rough or porous walls and dark base colours soak up more – be a bit conservative.
Do I really need two coats?
Almost always, if it's a new colour or a fresh wall. Going dark to light can even need 3 coats.
Does the calculator include primer?
It calculates the number of coats you enter. If you need to prime first, run a separate calculation for 1 primer coat.
Should I subtract windows and doors?
You can, if they take up a lot of the wall. Leaving them in just means a little extra paint in reserve – usually not wasted.
Use the results in a real project
With MyPlanDIY you can save materials, create budgets, track tasks and bring everything together in one project.
No credit card required. Free demo project included.
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