Red is an energetic and emotional colour, according to the colour theory website ColorLab.com. Pair it with the right wall colour to prevent it from overwhelming a room. There are several colours that will look great with a red sofa, and one that will not---red.
Gray is a neutral colour that creates a sophisticated and classy look when paired with a red sofa. Use a dark grey shade, such as Studio Gray by Ralph Lauren Paint, to prevent the red from looking out of place.
According to colour theory website ColorLab.com, yellow is a joyful and lively colour. Pair your red sofa with yellow walls for a warm and happy atmosphere. Try Gone Bananas from Olympic Paint at Lowe's.
Blue is a calming colour, according to ColorLab, but a light blue shade (think robin's egg blue) paired with your red sofa will instantly turn the room into a cheerful space with a playful atmosphere. Check out Skyscraper by Benjamin Moore.
Green walls with your red sofa will give the room a modern take on elegance, but choose crisp, light green shades like mint or sage to prevent a year-round Christmas look. Try Sounds of Nature by Benjamin Moore.
Tan is a basic wall colour that you're not likely to get sick of too soon, and with the red sofa, it creates a classic, comfortable atmosphere. Try Earthy Cane by Olympic.