How much wall a tin of paint covers

Every tin of paint carries a coverage figure, usually in square metres a litre. It tells you how much wall the paint will cover in one coat, in good conditions. That figure is the starting point for every question about how far a tin goes, from a 30 ml tester pot to a 10 litre tub. It is also an honest best case, and real walls nearly always take more.

This guide gives the coverage for each common tin size, explains why your own walls may take more than the label suggests, and shows how to turn one tin into a number of tins for a room. The calculator works it out for any tin, paint and number of coats.

How much a tin covers, by size

The table uses 14 square metres a litre for matt emulsion on a smooth, sealed wall, which is the rate printed on many emulsion tins, and 12 square metres a litre for eggshell, satin and gloss. Most walls need two coats, so the two-coat columns are the ones to plan from.

Tin	One coat, matt	Two coats, matt	Two coats, eggshell or gloss
30 ml tester	0.42 m²	0.21 m²	0.18 m²
50 ml tester	0.7 m²	0.35 m²	0.3 m²
250 ml	3.5 m²	1.75 m²	1.5 m²
500 ml	7 m²	3.5 m²	3 m²
750 ml	10.5 m²	5.25 m²	4.5 m²
1 litre	14 m²	7 m²	6 m²
2.5 litres	35 m²	17.5 m²	15 m²
5 litres	70 m²	35 m²	30 m²
10 litres	140 m²	70 m²	60 m²

Paint makers’ own figures for a 2.5 litre tin of emulsion run from about 25 to 35 square metres a coat, depending on the brand and the finish. If your tin states a lower rate, use that rate in the calculator rather than the table.

Reading the coverage figure on the tin

Tins in the UK, Europe, South Africa and Australia state coverage in square metres a litre, sometimes as a range such as 12 to 14. American cans state square feet a gallon. Either way, the figure assumes a smooth, sound wall that has already been painted or sealed, a colour not far from the one underneath, and paint laid on at the thickness the maker intends.

When the tin gives a range, plan from the lower number. The higher one is what a skilled decorator gets on an ideal surface, and on a large room the gap between the two can be a whole extra tin.

Why your walls take more than the label says

Coverage falls for a handful of reasons, and most walls have at least one of them.

• New plaster and bare surfaces. Fresh plaster, bare wood and new plasterboard are porous and soak up the first coat. Most paint makers ask for a thinned first coat, often called a mist coat, or a primer or sealer, mixed and applied as the tin directs. Plan on about 6 square metres a litre for that first coat on bare plaster.
• Texture. Textured walls, woodchip, pebbledash and masonry have far more surface than their flat measurements suggest. Exterior masonry paint usually covers about 8 square metres a litre, and rough or textured masonry about 6.
• A big colour change. Covering a dark or strong colour with a light one, or going from white to a deep red or yellow, often takes a third coat. A primer tinted towards the new colour can save one of them.
• Rollers and trays. A thick-pile roller holds more paint than a short-pile one, and every roller, brush and tray keeps some of the paint you pour.
• Stretching the paint. Rolling paint out too thin to make a tin go further leaves a patchy finish, and the extra coat it needs uses more paint than the stretching saved.

A common allowance is about 10 percent on top of the calculated amount, and more for a first coat on bare plaster.

How many coats you need

Two coats is the standard for walls and ceilings. The first coat covers the surface and the second gives an even colour and sheen. One-coat paints are thicker and can manage on a sound surface in a similar colour, but they still need two coats over a strong colour change or a repair.

Woodwork painted in gloss or satin over an old finish usually takes an undercoat and one topcoat, or two topcoats where the colour is staying the same.

How the calculator works

The calculator starts from the tin and works forward to the wall. It multiplies the size of the tin by the number of tins to get the litres you have. It then multiplies the litres by the coverage rate in square metres a litre, which gives the area that paint covers in one coat. Last, it divides that area by the number of coats, because every coat uses the same paint again over the same wall.

In symbols, area at one coat = litres × rate, and finished area = litres × rate ÷ coats. Square feet are square metres × 10.764. To show what the area means on an ordinary wall, the calculator also divides the finished area by 2.4 metres, a common ceiling height, to give a length of wall.

With the defaults, one 2.5 litre tin of matt emulsion at 14 square metres a litre covers 2.5 × 14 = 35 square metres in one coat. Over two coats that is 35 ÷ 2 = 17.5 square metres, about 188 square feet, or a wall about 7.3 metres long and 2.4 metres high.

The limits are the ones in the section above. The rate on a tin is for a smooth, sealed surface in a similar colour, so new plaster, texture and a large colour change all cover less. Choose a lower rate in the calculator for those walls, or add a coat.

Tester pots: what 30 ml really covers

A 30 ml tester pot holds 0.03 litres. At 14 square metres a litre, that covers about 0.42 square metres in one coat, which is enough for two coats on a patch about 45 cm square. A 50 ml pot covers about 0.7 square metres in one coat.

A patch that size is worth the effort. Paint two patches on different walls, one near the window and one in the darkest corner, and look at them in the morning, in the afternoon and under lamplight before you choose. A colour on a small card can look very different across a whole wall.

US cans: quarts and gallons

A US gallon holds 3.785 litres and a quart holds 0.946 litres. American labels usually state 350 to 400 square feet a gallon for one coat, on a smooth, primed wall in a similar colour. That is about 8.6 to 9.8 square metres a litre, lower than many UK and South African emulsion tins state, which is one more reason to plan from the figure on your own tin.

On new drywall, a gallon usually covers nearer 250 to 350 square feet, and a gallon of primer about 200 to 300 square feet. A quart covers about a quarter of a gallon’s area, roughly 90 to 100 square feet in one coat. The calculator includes both can sizes and a US label rate.

From one tin to a whole room

The coverage of a tin answers how far it goes. For a whole room, the question turns round: how much paint the walls need. For that, measure the distance around the room and multiply it by the height of the walls. Take off about 1.5 square metres for each door and 1.4 square metres for each window, multiply by the number of coats, and divide by the coverage rate.

The paint calculator does that sum and turns the litres into a number of tins. Use it for the room, and come back to this guide’s calculator to check what any spare tin will cover.

Buying the right number of tins

Buy enough for every coat, plus the allowance, in one go. Paint mixed to the same colour at different times, or from different batches, can differ slightly. If you do end up with more than one batch, pour the tins into a larger bucket and stir them together before you start, so the whole wall comes from one mix.

Keep a little of the leftover paint for touch-ups, with the colour name and the room written on the lid. Close the lid firmly and store the tin somewhere frost-free, because emulsion that freezes can spoil.