A rug that’s too small makes even a beautiful room feel disconnected — it’s one of the most common decorating mistakes designers see. The front legs of your furniture should rest on the rug, not dangle off its edge, but few people know the actual numbers. Our rug size calculator gives you those numbers in seconds.

Standard rug sizes exist for a reason: they map to standard room layouts. But ‘standard’ only helps if you know which one fits your space. Instead of guessing between a 5×8 and an 8×10, enter your room dimensions and get a clear, designer-approved recommendation. For more room-by-room guidance, see The Spruce’s ultimate rug size guide.

How the rug size calculator works

Enter your room’s length and width, and the calculator recommends the ideal rug size based on professional placement rules — typically leaving 12 to 18 inches of bare floor around the edges. It accounts for furniture groupings too, so whether you’re anchoring a sectional or defining a dining zone, the proportions come out right.

Size first, style second

Here’s the insider order of operations: nail the size before you fall in love with a pattern. A perfectly sized simple rug always looks better than a gorgeous rug that’s two feet too small. For inspiration on pulling the whole room together, browse our modern luxury living room ideas — you’ll notice every featured space gets the rug proportions exactly right.

Get the size right and everything else falls into place.

Rug size calculator FAQs

What is the most common rug size mistake? Buying too small. When in doubt, size up — a rug that fits under the front legs of all seating always looks more intentional.

How much bare floor should show around a rug? Aim for 12 to 18 inches of bare floor between the rug edge and the walls in a living room.

Should the rug go under the sofa? Ideally, yes — at least the front legs of the sofa and chairs should rest on the rug to anchor the seating group.