How Many Litres of Paint per Square Metre?

If you work in metres and litres, the question how many litres of paint per square metre is really two questions. First, how many square metres will one litre cover on your walls, and second, how many square metres do you actually have? Get both halves right and buying paint becomes simple arithmetic. Get either half wrong, usually by trusting the optimistic figure on the tin, and you run short. This guide uses metric measurements throughout. If you would rather let a tool do the sums, our paint calculator has a metric mode that works in litres and square metres.

The direct answer

Plan on about 12 square metres per litre per coat for emulsion on previously painted walls. That single planning figure answers most of the question. The tin often claims 13 to 14 square metres per litre, but that is a smooth-surface laboratory figure, measured under ideal conditions on a sealed, flat test panel. Real walls have texture, repairs, edges and a little thirst, so they cover less. Using 12 rather than 14 builds the shortfall into your estimate before you buy, instead of discovering it with one wall left to finish.

To turn coverage into a purchase, divide your wall area in square metres by the coverage figure to get litres per coat, then multiply by the number of coats. A wall area of 36 square metres, for example, needs about 3 litres per coat at 12 square metres per litre, and about 6 litres for the usual two coats. Round up to tin sizes you can actually buy, and keep a little spare for touch-ups.

Coverage by paint type

Different paints spread at different rates, so use the row that matches the product in your hand rather than one figure for everything.

Paint type	Claimed coverage	Plan on
Vinyl emulsion	12-13 m² per litre	10-12 m² per litre
Primer and undercoat	10-12 m² per litre	About 10 m² per litre
Gloss and satinwood	14-17 m² per litre	12-14 m² per litre
Masonry paint	6-10 m² per litre	The lower end on rough render

Gloss and satinwood go further because they are used on smaller, smoother areas such as doors and trim, and they are applied more thinly. Masonry paint goes the shortest distance because exterior render, pebbledash and brick soak up paint and present far more surface than their flat measurements suggest. When a surface is rough, always plan from the bottom of the range.

Measuring a room in metres

For a rectangular room, the wall area is 2 multiplied by (length + width), multiplied by the ceiling height. In words: add the length and width, double it to get the distance around the room, then multiply by how tall the walls are. Deduct roughly 2 square metres for a standard door and about 1.4 square metres for a standard window if you want a tighter figure, although many people leave small windows in the total as a built-in allowance for waste and cutting in.

Worked example: a 4 x 3 metre bedroom

Take a bedroom that measures 4 metres by 3 metres, with a ceiling height of 2.4 metres. The wall area is 2 x (4 + 3) x 2.4, which is 33.6 square metres. At a planning coverage of 12 square metres per litre, one coat needs 33.6 divided by 12, which is about 2.8 litres, so call it 3 litres per coat. A 5 litre tin therefore covers roughly one coat plus touch-ups. Two coats want about 6 litres in total, so buy 2 x 5 litre tins or a single 10 litre tub and keep the spare, sealed and labelled, for future touch-ups. You can check the same room in seconds with the paint calculator set to metric.

Why real coverage falls short

Porous new plaster

New plaster is thirsty. The first coat sinks in unevenly, which is why decorators apply a mist coat of thinned emulsion before the full coats. That extra, thinner coat uses paint you did not count if you only budgeted for two standard coats, and unsealed plaster can reduce effective coverage well below the planning figure.

Texture

Stipple, heavy roller texture, exposed brick and rough render all present more real surface than a flat measurement suggests, and paint has to fill every dip. The rougher the wall feels under your palm, the closer you should plan to the bottom of the coverage range, or below it.

Dark over light, and light over dark

Strong colour changes hide poorly at first. A deep colour over a pale wall, or a pale colour over a deep one, often needs an extra coat to look even, and every extra coat is another full set of litres. Budget the third coat before you start rather than hoping two will do.

Spraying

Spraying is fast and gives a smooth finish, but overspray and bounce-back waste paint that a roller would have put on the wall. If you spray, expect to use noticeably more paint than the roller figures in this guide, and mask everything you do not want coated.

How many litres should you actually buy?

Buy for the job in one visit, in one batch where you can. Work out the litres for two coats from the planning figure, round up to the tin sizes on the shelf, and accept a modest leftover. Leftover paint, stored sealed with the room name and date on the lid, is not waste: it is the only reliable way to touch up a scuff later in exactly the same colour and sheen. Running short, by contrast, risks a slightly different batch on the final wall, which shows most in raking light.

A quick US note

If you are comparing figures from American sources, one US gallon is about 3.79 litres and covers about 32 square metres per coat. That is consistent with the planning figures above once you convert the units. Our companion guide on how much paint do i need works through the same method in gallons and square feet, and our guide to paint coverage per litre explains in more depth why the achieved figure so often differs from the printed one. For a final check before you buy, run your room through the paint calculator in metric mode.

Frequently asked questions