What colour art goes above a grey sofa — and five other sofas.

Conventions, not rules. The proportions here are what galleries and interior designers have settled on because they work in most rooms. They are a starting point for your room, not a law. Where a convention is commonly broken for good reason, we say so.

Grey sofa

Grey is a neutral that leans, and which way it leans decides everything. Hold a sheet of white paper against it in daylight: a cool grey will look faintly blue or violet next to the paper, a warm grey faintly brown or green.

• Cool grey takes cobalt, teal, deep blue-green, and clean white. Warm ochres fight it and go slightly dirty.
• Warm grey takes terracotta, rust, mustard, olive and cream — the boho and mid-century palettes almost exactly.

Either way, grey is the most permissive sofa there is and its real risk is the opposite of clashing: a grey sofa, grey art and a grey rug produce a room with nothing to look at. Grey wants one saturated colour introduced deliberately, and art is the cheapest place to put it.

Beige, cream or oatmeal sofa

Warm by definition, so warm art. Terracotta, ochre, olive, dusty pink and every brown between them. The trap is matching too closely — beige art above a beige sofa disappears entirely from more than two metres away. Keep the palette family and increase the contrast: a botanical in deep green on cream, or an abstract with one strong burnt-orange field.

Navy or dark blue sofa

Navy behaves like a neutral but reads as a strong colour, so the art needs a light ground or it vanishes into the sofa in evening light. Brass, ochre and warm cream are the classic partners — opposite ends of the wheel, and the reason navy-and-gold looks expensive. Rust and coral work for a warmer version. Avoid mid-blue art directly above a navy sofa; two blues that are close but not the same is the worst outcome in the whole colour question.

Green sofa

Olive, forest and sage sofas have had a long run and they take colour well. Rust, terracotta and clay sit opposite green and warm the whole wall. Blush and dusty pink are the softer answer. Ochre works but keep it away from yellow-green. Botanical prints above a green sofa are the obvious choice and are usually a mistake — green on green flattens; the room wants a contrast.

Tan or brown leather sofa

Leather brings its own strong orange-brown, which behaves like a colour in the room rather than a neutral. Blue-greens, teal and deep petrol are its natural opposite and the reason those pairings read so well. Cream and off-white grounds keep it from feeling heavy. Skip orange and red; they compete with the leather rather than complement it.

Bold or patterned sofa

If the sofa is the loud object in the room, the art should not also be. Pull one colour out of the sofa's pattern and find art that uses it as a small accent on a quiet ground. A line drawing or a japandi palette is usually the right register here.

The useful part

Rooms don't fail because the art clashes with the sofa. They fail because the art is the fourth or fifth thing introducing a new colour, and nothing in the room repeats. The reliable move is the opposite of matching: find a colour already present somewhere small — a cushion, a book spine, a pot plant, the timber of the floor — and buy art that repeats it at scale. The room then looks planned, because something in it now rhymes.

That is exactly what the matcher does mechanically. It reads the actual colours out of a photo of your room, including the ones you stopped noticing, and shows you prints built on those colours rather than on a colour name.