Eye level, not the middle of the wall

The centre of a piece should sit at roughly eye level, about 145 to 150cm from the floor. That is a gallery convention and it works because it is based on the average standing sightline rather than on the architecture.

Above furniture the rule changes. Leave about 15 to 20cm between the top of the sofa or console and the bottom of the frame, so the two read as one group. Hung higher, the piece floats and the wall between them becomes a visible gap.

In a room where people are mostly seated, drop everything slightly. A dining room or a snug is looked at from a chair, and hanging at standing eye level there puts everything a little above where it should be.

For a group, treat the whole arrangement as one rectangle and centre that rectangle rather than any individual piece. Lay the group out on the floor first and photograph it, which is faster than any amount of measuring and immediately shows whether the spacing is even.

Spacing within a group should be consistent and tighter than instinct suggests: five to eight centimetres between frames reads as intentional, while fifteen reads as unrelated objects that happen to share a wall.