Most pictures in most homes hang too high and too small. The picture sits up near the ceiling where nobody looks, and a 30 by 40 cm frame floats alone above a two-metre sofa. Three numbers fix nearly all of it.
145 cm: where the centre goes
Galleries hang the centre of a picture at roughly 145 to 150 cm from the floor, which is a little below the eye level of an average adult standing up. It looks right because you see the picture straight on rather than looking up at it. Measure to the centre of the picture, not the top of the frame: for a 60 cm tall frame, the top edge ends up at 175 cm. Use the same centre line for every picture in a room and the wall stops looking random, whatever the frames are.
The exception is furniture. Above a sofa, a sideboard or a bed the picture belongs to the furniture, not to the eye line, and the next rule takes over.
15 to 25 cm: the gap above furniture
A picture above a sofa should hang 15 to 25 cm above the back of it, close enough that the two read as one group. Higher than that and the picture floats; lower and heads bump it. Above a bed, measure from the top of the headboard. Above a sideboard or a desk, 15 to 20 cm above the surface.
Two thirds: how wide
A picture, or a group of pictures, above a piece of furniture should be about two thirds to three quarters of the furniture’s width. Above a 200 cm sofa that means a picture or a group 130 to 150 cm wide, which is a big canvas, a pair of 60 by 80 frames, or three 50 by 70s in a row. A single 40 by 50 above a sofa is the most common mistake in the world, and the reason is simply that big prints look expensive in the shop. On a wall they are the cheapest way to make a room look finished.
On an empty wall with no furniture, the rule of thumb is that the picture or group should fill roughly half to two thirds of the wall’s width.
Fixings
Anything wider than about 60 cm wants two hooks, one each side, so it hangs level and stays level. Frames with D-rings on the sides hang straighter than frames with a single wire. On plasterboard, use the plug made for it rather than a nail. If you hang more than a few pictures, or you rent, a picture rail with adjustable cords does away with holes entirely and lets you move things by hand; Stas makes the rails most galleries and shops use, in a few finishes for home walls.
The measuring trick
Cut paper to the size of the frame, tape it to the wall where you think the picture goes, and live with it for a day. Then measure the centre. It costs nothing and it prevents the second hole.