Match the artwork to about two thirds of the bed’s width — roughly 100 cm of art above a double bed, 120 cm above a king — hung 15 to 25 cm above the headboard.
The bed decides the size. Match the artwork to roughly two thirds of the bed's width, and the wall stops looking empty.
For a double bed, 140 to 160 cm wide, that means about 100 cm of art: one 100×70 cm piece, or two 50×70 cm pieces side by side. For a king, 180 cm, go to 120 cm of art — a 84×119 cm piece hung in landscape, or three smaller pieces in a row.
Height: the bottom edge sits 15 to 25 cm above the headboard. Without a headboard, measure from the mattress and use 60 to 70 cm.
One piece or several? A single large piece is calmer, and calm is what a bedroom is for. Two or three smaller pieces give you a rhythm, but they need the gaps to be equal and the bottoms to line up, or the wall looks restless.
On subject: the bedroom is the room where people most often regret a bold choice. Work with low horizons, water, mist and colour fields tends to keep working after the first month, which is why so much of this collection lives in that register.
If you want to see it before deciding, every piece here can be viewed at true size against a bed in the room preview, and the size guide shows all sizes drawn to scale.