Paint calculator

How many litres for the walls and ceiling, shown on your room.

Your room

Metricft / in

Length

Width

Height

Wall colour

Sage

Paint the ceiling too

Buy 7.5 litres of wall paint.

Your walls are 34.3 m² after one door and one window. Two coats at 10 m² per litre need 6.9 L: one 5 L tin and one 2.5 L tin.

Walls

34.3 m²

Ceiling

Not painted

Paint needed

6.9 L

Try colours on your own floor plan

Free account. Or try the example flat, no account needed.

The short answer

Paint for a room is wall area times coats, divided by what one litre covers. The wall area is the room's perimeter times its height, less the doors and windows. A 4 × 3.5 m room with a 2.5 m ceiling has 37.5 m² of wall; take off one door and one window and about 34 m² is left. Two coats at 10 m² per litre is about 6.9 litres, so you buy a 5 L and a 2.5 L tin.

Ten square metres per litre (about 350 to 400 sq ft per US gallon) is a common figure printed on tins of interior emulsion; check yours, as thick colours, fresh plaster and rough walls take more. This calculator does the arithmetic, rounds up to the tins shops sell, and paints the walls of a 3D room in the colour you pick.

How to use it

1
Measure the floor and the height
Measure the room's length and width along the floor, and the height from floor to ceiling. Round up to the next 10 cm or half foot.
2
Count the doors and windows
The usual one door and one window are already taken off. Change the counts, the coats or the coverage from your tin under More options, and tick the ceiling if you're painting it too.
3
Buy the tins, pick a colour
The answer is the tins to buy, rounded up to the sizes shops sell, with the wall and ceiling area. Tap a colour to see it on the walls of the room.

Questions

How much paint do I need for a room?

Work out the wall area (perimeter × height, minus doors and windows), multiply by the number of coats and divide by the coverage on the tin. An average bedroom of about 4 × 3.5 m with a 2.5 m ceiling needs about 7 litres for two coats on the walls; a 12 × 14 ft room with an 8 ft ceiling about 2 US gallons.

How much does a litre of paint cover?

Most interior emulsions say about 10 to 12 m² per litre for one coat, and US wall paints about 350 to 400 sq ft per gallon. It's less on new plaster, bare wood, textured walls and with a roller loaded heavily. Use the figure on your tin: you can type it under More options.

How many coats of paint do I need?

Two is the rule of thumb for walls: the first evens out the surface, the second gives the colour. A third helps when going from dark to light or with strong colours like reds and yellows. New plaster wants a thinned mist coat first, which counts as a coat here.

What sizes do the doors and windows have?

The calculator takes off 85 × 205 cm (about 2′ 9″ × 6′ 9″) for each door and 120 × 120 cm (about 4 × 4 ft) for each window. Big patio doors or bay windows take off more; if you have one, count it as two.

Should I buy extra paint?

Rounding up to whole tins usually leaves you some spare for touch-ups. If the amount needed is close to the tins' total, buy one small tin more: running out halfway through a wall is worse, and a second batch can differ slightly in shade.

Can I try paint colours on my own floor plan?

Yes. Upload your floor plan and UploadFloorplan builds it in 3D with every wall, door and window. Then change the wall colour, add your furniture and see the room before you paint. A free account is enough.