The biggest wall in the house, and the one people undersize.

Size it to the furniture, not the wall

The reference point above a sofa is the sofa, not the room. The convention designers use is two-thirds: the artwork, or the whole arrangement, should span roughly two-thirds of the sofa's width. On a standard three-seater of about 210 cm, that is around 140 cm of art.

Which is much bigger than most people buy. A single A2 print is 42 cm wide. Three of them with 7 cm gaps come to 140 cm — so the honest answer above a three-seater is usually three A2s, one very large piece, or a 50×70 pair.

Height, when there is furniture below

The general rule is the centre of the art at 145 cm from the floor. Above a sofa it drops, because the art now relates to the furniture: leave 15–25 cm between the top of the sofa back and the bottom of the frame. On an 85 cm sofa that puts the bottom edge around 100–110 cm and the centre near 135 cm.

Below 15 cm and it looks stuck on; above 25 cm and the art floats away from the sofa and stops reading as a pair.

What suits the room

Living rooms are seen from a distance and usually from a seated position, which favours work that reads at range: mid-century for its bold flat shapes, abstract for the same reason, and boho where the room already has natural materials in it. Detailed work — botanical, fine line drawing — is largely wasted here; it belongs somewhere people pass close by.

If the wall is very wide

Resist filling it edge to edge. A wide wall wants one confident group in the middle with real empty space either side, not a thin band of small frames stretched across it. Scale up the pieces rather than adding more of them.