The most common living room rug sizes are 8′ x 10′ and 9′ x 12′. With very few exceptions, a 5′ x 8′ rug or 5′ x 7′ rug is too small for a living room.
If you have a smaller rug, like 5′ x 8′ or 5′ x 7′ already that you absolutely love and that goes beautifully with your decor, you can layer it on top of a large rug so that you get the overall area rug size your living room needs.