There are some general rules of thumb concerning area rugs that many people tend to follow, and for a good reason: they work. By work, what is meant, is that the room ends up looking proportional. One popular rule is that the rug should be large enough to slide under the front legs of sofas and chairs in a seating arrangement, unifying the furniture. Rather than being bound by rules, being aware of these guidelines and options will assist you in determining what size rug provides the visual effect you desire in the rooms of your house.
Rule 1: Front legs on the rug, back legs off. However, there are some cases where the front legs sit on the rug while others are off. This approach really does work in most situations; the rug connects the various furniture pieces together while extending far enough into the room to create a sense of good proportion.
Rule 2: You can have only the front legs of the sofa sit on the rug while the placement of the chairs leave all four legs firmly on the rug. This proves to be more effective if only the front legs of the chairs fit onto the rug, because of the size of the room and the contrasting tone of the rug against the flooring.
Rule 3: All legs on the rug. One tip is to determine the furniture placement prior to selecting what size rug to use, which leads to the next rule: A room generally looks more pulled together if all the furniture legs are planted firmly on the rug.
Rule 4: No legs on the rug. Now if you would like to bring in just a small rug, perhaps one that introduces a pop of pattern into the room, another approach would be to have none of the furniture touching the rug. While this creates a completely different look, it also works.
Rule 5: 18 inches of bare floor around the rug. The next rule has been a standard for ages, and this approach states that there should be approximately 18 inches of bare floor between the rug edge and the perimeter walls of the room, bringing in traditional proportion. This guideline is great in rooms that are enclosed and separate from surrounding rooms, as opposed to open concept spaces.
Rule 6: Just a few inches of floor around the rug. Here is a successful application of the rule to run the rug up to within inches of the wall around the entire room.
Rule 7: Extend the rug 12-18 inches around a bed. For an area rug to look balanced under a bed, it should be large enough to extend beyond the sides of the bed at least 18 inches for a king or queen bed and at least 12 inches for a full or twin bed. Depending upon the size of the room there can be more rug extension around the bed, but not less, which would make the rug look insignificant being covered mostly by the bed.
Rule 8: Cover the walking area. The rug should cover the majority of the walking area in a hallway or entry. For both safety and comfort, it is preferable to have both feet fall within the surface of the rug in a high traffic area.
Keep in mind that there are multiple rules to guide the decision of what size rug is best for the rooms of a home and many of them completely contradict one another. But being aware of the various rules can provide guidelines to help determine which approach is most appealing to you and will be effective in achieving the look you desire in your individual spaces.
I always say you can use any rug that you want to, as long as it looks to scale. Use common sense rather than trying to follow a bunch of rules. You can tell if a specific rug looks silly in a room. And if you want to find a new rug, try hitting Craigslist. People sell their rugs there for next to nothing.
Area rugs really can be expensive. Lowe's actually has a great sisal rug in 9 x 12 that they sell. It costs much less than most other area rugs. Don't forget to check it out. It comes with several options regarding the border. Red, blue, black, tan. Pretty much every color. I think they offer free shipping too, but don't quote me.