How Much Paint Do I Need per Square Metre? UK Guide

Quick answer: Most UK emulsions cover 10 to 17 square metres per litre per coat, and 13 m² per litre is a common figure for standard matt. At that rate each square metre needs about 0.08 litres per coat, or roughly 0.15 litres for the usual two coats. Always check the spreading rate printed on your tin.

Buying paint is a measuring job before it is a decorating job. You need the area of the surface, the number of coats and the coverage figure from the tin, and the rest is one line of arithmetic. This guide is part of our home and DIY measuring guides, and it gives you a calculator, a quick-reference chart and a fully worked bedroom example.

Paint calculator (walls of one room)

Room length (m) Room width (m) Wall height (m) Doors and windows to deduct (m²) Coats Coverage on tin (m² per litre) =4.35 litres (paintable area 28.25 m²)

The calculator multiplies the room's perimeter by the wall height, takes off the doors and windows you enter, multiplies by the number of coats and divides by the coverage. Round the answer up to the next tin size. For a ceiling, use length × width as the area instead.

Treat the four walls as one long strip: perimeter × height, minus doors and windows, times coats, divided by the coverage on the tin.

Table of Contents

How much paint do you need per square metre?

At a coverage of 13 m² per litre, one square metre needs 0.077 litres (77 ml) per coat. The general formula is litres = area × coats ÷ coverage, where coverage is the spreading rate in square metres per litre printed on the tin or the product page.

That spreading rate varies more than people expect. Dulux lists its Simply Refresh One Coat matt at up to 10 m² per litre because it is designed to go on thickly, while Dulux Walls & Ceilings matt is listed at 13 m² per litre and Crown Trade Vinyl Matt at up to 17 m² per litre. The words "up to" matter: the figure assumes a smooth, sealed surface and careful application.

How do you measure a room for paint?

Measure each wall's width and the floor-to-ceiling height, multiply, then subtract doors and windows. Measuring to the nearest 5 cm is plenty.

What you need

A tape measure of at least 5 m (see how to read a tape measure if the markings are unfamiliar)
The paint's spreading rate in m² per litre

Measure the wall widths. Run the tape along the skirting of each wall and add the four figures to get the perimeter.
Measure the height. Go from the top of the skirting to the ceiling, or to the picture rail if you are painting only the lower section.
Multiply. Perimeter × height gives the gross wall area in square metres.
Deduct openings. Multiply each door and window's width by its height and take them off.
Apply coats and coverage. Multiply by the number of coats, divide by the spreading rate and round up to the next tin.

If you would rather work in square feet, the area converter switches between m² and ft² instantly. The same measuring habits apply to measuring a room for wallpaper, so it is worth noting the figures down if you might do both.

How much paint does a typical bedroom take?

A 3.5 m × 3 m bedroom with 2.4 m walls needs about 4.35 litres of standard matt emulsion for two coats on the walls. The perimeter is 13 m, so the gross wall area is 31.2 m². Taking off one standard 762 mm × 1,981 mm door (1.51 m²) and a 1.2 m square window (1.44 m²) leaves 28.25 m². Two coats double that to 56.5 m², and 56.5 ÷ 13 = 4.35 litres, so a single 5 litre tin covers it with a little to spare.

The ceiling is a separate sum: 3.5 × 3 = 10.5 m², and two coats at 13 m² per litre come to 1.62 litres, which means a 2.5 litre tin of ceiling or matt white.

Paint quantity chart: litres for two coats

Find your paintable area in the left column and read across to the coverage on your tin. Figures are for two coats; halve them for one.

Area to paint	Area (sq ft)	At 10 m²/L	At 13 m²/L	At 16 m²/L
5 m²	54 sq ft	1.00 L	0.77 L	0.63 L
10 m²	108 sq ft	2.00 L	1.54 L	1.25 L
15 m²	161 sq ft	3.00 L	2.31 L	1.88 L
20 m²	215 sq ft	4.00 L	3.08 L	2.50 L
25 m²	269 sq ft	5.00 L	3.85 L	3.13 L
30 m²	323 sq ft	6.00 L	4.62 L	3.75 L
40 m²	431 sq ft	8.00 L	6.15 L	5.00 L
50 m²	538 sq ft	10.00 L	7.69 L	6.25 L
60 m²	646 sq ft	12.00 L	9.23 L	7.50 L
80 m²	861 sq ft	16.00 L	12.31 L	10.00 L

How many coats of paint do walls need?

Plan on two coats for most walls. Two coats give even colour and hide roller marks; Dulux, for example, specifies two coats for its EasyCare Washable & Tough range. One-coat products are the exception, and they achieve it by going on thicker, which is why their coverage per litre is lower.

Bare new plaster is very absorbent, so manufacturers recommend either a thinned first coat (often called a mist coat) or a product made for new plaster. Follow the tin rather than a generic ratio.

What makes paint go further or less far?

Rough, porous and dark surfaces all cut coverage. Woodchip, Artex and render have far more surface than their flat area suggests, new plaster and bare wood soak up the first coat, and a dark-to-light change usually costs an extra coat. Spraying also loses some paint to overspray.

How do you convert US coverage figures to m² per litre?

Divide square feet per US gallon by 40.75 to get square metres per litre. American paint advice usually quotes 350 to 400 square feet per gallon, which works out at about 8.6 to 9.8 m² per litre. For a UK (imperial) gallon the divisor is 48.93, because an imperial gallon is 4.54609 litres rather than 3.785 litres.

In the UK, paint itself is sold in litres, typically 2.5 litre and 5 litre tins for walls, 10 litre tubs for bigger jobs and 750 ml tins for wood and metal. Square feet still turn up in older decorating books and on American videos, so the litres to gallons converter is handy if you are following one.

Common mistakes to avoid

Using the floor area instead of the wall area; in a typical room the walls are two to three times larger.
Forgetting to multiply by the number of coats.
Assuming every paint covers the same area; check the tin each time.
Buying the exact amount with nothing left for touch-ups.

Frequently asked questions

How many square metres does 1 litre of paint cover?

Most UK wall emulsions cover between 10 and 17 square metres per litre per coat, depending on the product. The exact figure is printed on the tin as the spreading rate.

How much paint do I need for a 10 square metre wall?

At 13 square metres per litre, a 10 square metre wall needs 0.77 litres for one coat or 1.54 litres for two coats, so a 2.5 litre tin is enough.

Is 5 litres of paint enough for a bedroom?

Usually yes for the walls of a small or medium bedroom. A 3.5 by 3 metre room with 2.4 metre walls needs about 4.35 litres for two coats at 13 square metres per litre. Larger rooms, dark colours or rough walls may need more.

Should I deduct doors and windows when measuring for paint?

Yes. A standard internal door is about 1.5 square metres and a typical window 1 to 2 square metres, so deducting them stops you overbuying. Skip openings smaller than about half a square metre.