Buying too little means a second trip; buying too much wastes money. Here is the quick way to get it right before you open a tin.
The two most common ways a decorating job goes wrong before the brush is even wet are buying too little paint and buying too much. Run short halfway up a wall and you are back in the shop hoping the next tin matches; over-order and you have half-full cans cluttering the shed. A minute with a tape measure saves both.
The quick formula
Measure the height and width of each wall, multiply them together for the area in square metres, and add them up. Do not bother subtracting small windows and doors — the extra gives you a sensible margin. Then divide the total by the coverage on the tin.
As a rough guide, a litre of emulsion covers around ten to twelve square metres per coat on a smooth, sealed surface. Most walls want two coats, so double your figure. A typical 3m by 4m bedroom with 2.4m ceilings works out at roughly 34 square metres of wall — call it 5 litres for two coats, with a little spare.
What changes the numbers
- Porous or bare surfaces — new plaster, filler and old distemper drink paint, so coverage drops and a mist coat comes first.
- Dark to light, or a strong colour — you may need an extra coat, which means more paint.
- Texture — woodchip, heavy patterns and rough render all use more than smooth plaster.
- Ceilings and woodwork are separate — measure and buy for those on top of your wall figure.
A word on spare paint
Keep a labelled bit of each colour back for touch-ups — scuffs and knocks are inevitable and a dead match a year later is almost impossible. Store it somewhere frost-free with the lid firmly on.
Not sure? Bring your measurements to the counter and we will work out exactly what you need, including the right primer for the surface. No upselling — just enough paint to do the job properly.
