How much paint do I actually need?

Paint tins quote coverage as “up to” a figure. That assumes a smooth, sealed, previously painted wall and an unhurried roller. Bare plaster, a strong colour change or a textured surface all drink more, which is the usual reason people run out three quarters of the way round.

Only two of the forty eight paints we hold publish a range. For the rest, the single number on the tin is the best case. So rather than pretend to read a lower figure that does not exist, we take what the manufacturer publishes and work to about ten per cent less, then round up to whole tins.

That ten per cent is our decision, not theirs. It is the usual trade allowance for wastage and absorption. You will normally have a little left over, and that is deliberate: a spare half litre for touching up costs a few pounds, while running out mid wall costs an afternoon and risks a visible join where the new tin starts.

Coverage varies more than people expect, from around 10m² a litre for some gloss finishes to 18m² for some trade emulsions. Choosing the right paint in the list matters more than measuring to the nearest centimetre.