Paint Coverage Calculator
Estimate how many litres of paint you may need for walls and ceilings, including coats, windows, doors, and a waste allowance.
EmbedEach door subtracts ~1.9m2
Each window subtracts ~1.4m2
Check your paint tin - typically 10-16m2/L
How to Use This Paint Coverage Calculator
This paint calculator helps estimate how much paint you may need for a room or similar space before you buy supplies. It takes room dimensions, ceiling height, doors, windows, coats, and paint coverage into account so you can get a more realistic quantity than a simple rough guess.
Enter the room length, width, and ceiling height first. Then add the number of doors and windows so the estimate can reduce the non-paintable area. Choose how many coats you expect to apply, enter the paint coverage rate from the tin, and decide whether the ceiling will be painted as well as the walls.
The calculator shows net wall area, ceiling area, total paintable area, litres needed, and a small waste allowance. That is useful for avoiding the two common painting mistakes: buying too little and having to rush back for more, or buying far more than the job realistically needs.
Why Coverage Rates Matter
Different paints cover differently. Surface texture, existing colour, wall condition, and the number of coats can all change how much paint you actually use. That is why checking the paint tin and using a sensible buffer is usually better than relying on a generic rule of thumb.
Best Use of the Result
Treat the result as a planning estimate and round sensibly for the container sizes available. Buying a little extra is often worthwhile for touch-ups later, especially if colour matching could be difficult in the future.
Formula
Litres needed = total paintable area x number of coats / coverage rate, plus waste allowanceFrequently Asked Questions
How many coats of paint do I usually need?
Two coats are common for many rooms, but some jobs need more, especially when covering dark colours, painting new surfaces, or using lighter top coats over a stronger base. The right answer depends on the surface and paint type.
Should I buy extra paint?
Usually yes. A small buffer helps with touch-ups, uneven absorption, minor mistakes, and future repairs. It is often easier to keep a little left over than to match a colour later if you run short.
Do doors and windows make a big difference?
They can, especially in smaller rooms where the openings take up a meaningful share of wall space. Subtracting them helps produce a more realistic estimate instead of assuming the whole wall area needs full coverage.
Why might I use more paint than the calculator says?
Real-world usage can increase if the surface is porous, textured, damaged, or changing from a very dark colour to a lighter one. Painter technique and product quality also affect actual coverage.
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