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.
Placing a rug under the whole bed frame.
A 12 foot by 15 foot rug will look balanced under the longer california king size bed and this size area rug will even fit under nightstands.
This way it is easier to clean under bed especially for a teen boy.
How to place a rug under a bed.
As far as the under bed rug i like pelts either natural or faux instead of a rug that goes all the way under the bed.
Some people don t want to use a large rug under the bed but still want a soft place to land when getting out of bed.
A general rule of thumb suggests that an area rug should always extend at least 18 inches to 24 inches from the sides and from the foot of a queen size and a king size bed.
The best option in this case is to get a pair of runners for either side of the bed or else a pair of 3 5 rugs.
Make sure that the rug itself doesn t slide.
Ideally your rug will be wide enough to extend at least a few inches on either side of the bed s width.
If you need to go with a slightly smaller rug it should cover at least the area under the bed and give you a good 6 12 at the foot more if you have a bench or chest at the foot of your bed.
For this you can use a padding for rugs and even special grips that they sell for the padding.
If the head of your bed meets the wall the rug should start about a foot away.