Kings need a 9 × 12
A king is 16 inches wider than a queen, which pushes the rug from 8 × 10 to 9 × 12. An 8 × 10 under a king leaves 22 inches each side: it works, but only just.
If the room can't take a 9 × 12 with a foot of floor at the walls, two runners either side of the bed are the other classic answer.
Questions
What size rug for a living room?
Most living rooms with a standard 84 in sofa take an 8 × 10 ft (200 × 290 cm) rug with the front legs of the seating on it. With every leg on the rug, or a sofa over 90 in, go to 9 × 12. Leave 12 to 18 inches of floor between the rug and the walls.
How far should a rug go past the sofa?
At least 6 inches past each end, 12 if you can. A rug narrower than the sofa makes the room look smaller.
What size rug for a queen bed?
An 8 × 10 ft rug laid sideways under the lower two thirds of the bed, which gives about 18 to 24 inches of rug each side. For a king, a 9 × 12.
How big should a dining room rug be?
At least 24 inches past every edge of the table, so chairs stay on the rug when pulled out. A 40 × 72 in table needs at least 88 × 120 in: an 8 × 10 ft rug.
How much floor should show around a rug?
12 to 18 inches in most rooms, down to 8 in a small one. Less than that and the rug looks like wall-to-wall carpet that didn't fit.
What are standard rug sizes?
In the US: 3 × 5, 4 × 6, 5 × 8, 6 × 9, 8 × 10, 9 × 12, 10 × 14 and 12 × 15 ft. In Europe: 80 × 150, 120 × 170, 160 × 230, 200 × 290 (or 200 × 300), 240 × 340 and 300 × 400 cm.