A bedroom rug does one job: it gives your feet something soft to land on when you get up. That is why the size is not about the rug at all. It is about how much of it is left showing once the bed sits on top. Too small and it peeks out like a doormat, too big and it runs into the wardrobe.
Measure the bed, then think about the rug as the bed plus a border. A common rule of thumb from rug sellers and interior writers is to leave about 50–60 cm of rug showing beside each side of the bed and at the foot. That is roughly one comfortable step, so your feet find rug rather than cold floor.
Because the bed is wider than most people expect, this gets big quickly. A 160 cm wide bed plus 60 cm on each side is a rug at least 280 cm wide if the whole bed sits on it, which is bigger than most standard rugs. That is why the second option below is so popular.
Under the whole bed. The rug starts at or near the headboard and extends past the sides and the foot. It looks calm and complete, and it needs the biggest rug.
Under the bottom two-thirds. The rug starts about a third of the way down the bed, so the head end stays on the bare floor. You get the border you need at the sides and the foot with a much smaller rug, and the headboard end is no longer fighting the wall. This is the most budget-friendly layout, and it works with rugs you may already own.
Standard rug sizes in many European shops are around 160 × 230 cm, 200 × 290 cm and 240 × 340 cm, though makers vary. Use the planner to see what each one gives you.
When you swing your legs out of bed, your feet land beside the mattress and your first step goes a little further on. If the rug stops short of that, you step from warm rug to cold floor. About a step's worth of rug showing covers it, and it makes the bed look anchored rather than perched. It is a rule of thumb, not a law, so a little less is fine in a small room.
Try it in the planner. A 160 cm king bed on a 200 × 290 cm rug leaves 20 cm showing at each side. That is under the rule, so the rug looks like a mat beneath the bed. Switch to 240 × 340 cm and the sides become 40 cm, much closer. A 140 cm double on 200 × 290 cm gets 30 cm each side, and a 90 cm single gets 55 cm.
If the bed is pushed against a wall, only one side matters. A rug runner, about 70 cm wide, running along the open side does the job for much less money than a full-size rug.
In a small room, a rug that nearly fills the floor can make it feel smaller and bump into doors. Two small rugs, one on each side, are a flexible alternative, and you can often make them from rugs you already own.
Already own a rug? Rearrange before you buy. Moving it from the living room to under the bottom two-thirds of the bed is free, and the planner will tell you if it is big enough.
Whatever you choose, think about the tripping risk. Use a non-slip pad underneath, make sure the rug edges lie flat, and check the thickness: a thick pile can catch the bottom of a door or a drawer.
Whether you are spending a little or a lot, a few things matter most:
The pricier rugs tend to differ in materials and construction. A bigger rug costs more in any material, so the size you pick often matters more to your budget than anything else.