What size does your wall actually need?

01Measure the wall, not the painting

Start with the space the painting will occupy, not with a size you have seen elsewhere. Measure the clear width and height of the wall, then subtract what must stay empty: a hand's width of margin on each side at minimum, more if the wall is broken by a switch, a beam or a door frame.

What remains is the envelope. Every size that fits inside it is a candidate; every size that does not is out, however good it looks on screen.

02Above furniture, aim for two thirds

Over a sofa, a console, a bed head or a sideboard, a single painting looks right when it spans roughly two thirds to three quarters of the furniture below it. Narrower and it reads as an afterthought; wider and it overhangs, which the eye registers as a mistake even when it cannot name it.

A 200 cm sofa therefore wants something in the region of 130 to 150 cm across. That is a starting point, not a law, and the wall always overrules it.

03Ten sizes, one set of proportions

The sizes on a product page look irregular on purpose: 37 x 30, 62 x 50, 125 x 100. Nothing here is cropped or stretched to fit a standard frame, so both dimensions move together and the painting keeps the shape its composition was built for.

That is why the ten sizes differ from one painting to the next. A tall portrait and a wide landscape do not share a table, and neither is forced into the other's shape. The panel calculates both dimensions before you buy, in centimetres or in inches.

04Test it before you order

Mark the outline on the wall with masking tape, or cut it out of newspaper and tape it up. Then look at it from the three places you will actually see it from: the doorway, the nearest seat, and the longest sightline in the room.

Leave it there for a day. Most people who do this move up one size, and almost nobody moves down.

05Hanging height

Hang the centre of the painting at about 145 to 150 cm from the floor, which is eye level for most adults standing, and is the height galleries use. Above a sofa or a sideboard, drop that so the bottom edge sits 20 to 30 cm above the furniture: the two should read as one group rather than two objects that happen to share a wall.

06When to go bigger

Undersizing is the regret we hear about; oversizing almost never is. Go up a size when the wall is wide and otherwise empty, when the ceiling is high, when the painting is seen from more than four or five metres, or when it is the only thing on that wall. Go down when the wall is broken up, when the room is small and the viewing distance short, or when the painting will hang beside others.

Cost is not a reason to hesitate over a big canvas: shipping is free at every size, so the only difference between 100 cm and 150 cm is the price of the painting itself.