This rug size calculator takes a room and a furniture layout and returns the rug dimensions that fit, using the placement conventions interior designers actually work to. It then snaps the answer to the nearest size rugs are manufactured in, because a 10 ft 4 in by 8 ft 7 in rug is not something you can buy off a shelf.
Arb Digital built it because rug sizing is the most common furnishing mistake, and it is a geometry problem rather than a taste problem. Almost everyone buys too small. The rug then floats in the middle of the floor with every piece of furniture stranded around it, and the room reads smaller than it did with bare boards.
What This Rug Size Calculator Does
It applies one of four placement rules and reports both the exact dimensions that rule produces and the nearest standard rug size at or below it. It also tells you how much bare floor is left on the long and short sides, the rug's area, and the diameter of a round rug that would work in the same space.
This is furnishing geometry, not floor covering. Our carpet calculator works out how much material a wall-to-wall installation needs including waste and seam allowance, and the flooring calculator does the same for boards and planks. Neither of those is trying to leave a deliberate margin of bare floor, which is the whole point of a rug. If your room is not a clean rectangle, measure it with the square footage calculator first and bring the rectangle that contains the seating area back here.
How to Use It
- Choose the placement rule. Border rule for an open room you want mostly covered; all legs on or front legs on for a defined seating group; dining for a table.
- Measure the room. Wall to wall, at floor level, not at skirting height. Take the shorter of two readings if the walls are not quite parallel.
- Measure the furniture group. For seating, the rectangle that contains every piece of the conversation area. For dining, the tabletop including any leaves you leave in.
- Set the margin and the tuck. The margin is bare floor you want to keep. The tuck is how far the rug slides under a sofa on the front-legs-on rule.
- Read the standard size, then check the margins. If the bare floor figure comes out under about 6 inches on any side, the rug is crowding the walls and the next size down will look better.
The Formulas and How They're Calculated
Each rule is a subtraction or an addition on one pair of numbers. The border rule is rug = room − 2 × margin on both dimensions, because the margin appears on both sides. The all legs on rule is rug = furniture group + 2 × overhang, so the rug extends past the outermost legs by the overhang on every side. The front legs on rule keeps the width and shortens the depth to group depth − 2 × tuck, the strip left on bare floor behind each opposing piece. The dining rule is rug = tabletop + 2 × pull-out, because a chair must still have all four legs on the rug once someone has pushed back to stand up. Three of the four rules round the answer down to the largest stock size that fits; dining rounds up, because falling short there is a functional failure rather than a cosmetic one.
Work the defaults through. A 14 ft by 12 ft room under the border rule with an 18 in margin gives 1.5 ft each side, so the rug wants to be 14 − 3 = 11 ft by 12 − 3 = 9 ft. No standard rug is 11 by 9, and the largest that fits inside it is 10 ft by 8 ft. That leaves (14 − 10) ÷ 2 = 2 ft at the ends and (12 − 8) ÷ 2 = 2 ft at the sides — a 24 in margin rather than the 18 in asked for, still well inside the normal range, over 80 square feet of rug.
The unit handling is exact rather than approximate. An inch is defined as exactly 25.4 millimetres, a definition adopted internationally in 1959 and maintained by NIST's SI Units – Length page, so metric mode converts without accumulating rounding error. That matters because rugs are sold in whole feet in some markets and whole centimetres in others: a 200 × 300 cm rug is not a 6 × 9 ft rug, it is about 6 ft 7 in by 9 ft 10 in.
The Three Seating Conventions, and When Each One Is Right
All legs on is the most generous and the most expensive. Every piece sits entirely on the rug, with a margin showing beyond the outermost legs. It reads as one unified island and suits a large open room, or one where the seating floats away from the walls. It needs a big rug, and usually pushes you into a 9 by 12 or larger.
Front legs on is the compromise that suits most real living rooms. The rug slides a short distance under the front legs of the sofa and armchairs, tying them into the arrangement, while the back legs stay on bare floor. It anchors the group at a fraction of the rug area, and because the tucked strip is hidden it does not matter that the rug is not quite deep enough for the full footprint. If you take one rule from this page, take this one.
Floating — all legs off, the rug entirely between the furniture — is the one that goes wrong. It works only when the furniture is genuinely against the walls of a small room. In anything larger, a rug no furniture touches looks like an accident, and that is the failure people misdiagnose as the wrong colour when it was the wrong size.
Dining Rooms: Why 24 Inches Is Not Negotiable
The dining rule is the least forgiving here, because there is a physical test it either passes or fails. Pull a chair back far enough to stand up and the back legs travel roughly 20 to 24 inches. If the rug edge falls inside that distance the legs drop off it, the chair rocks, and the edge catches and frays.
So the rug must extend at least the pull-out distance beyond every edge of the tabletop, on all four sides. A 72 in by 40 in table with a 24 in allowance needs 72 + 48 = 120 in by 40 + 48 = 88 in, which is 10 ft by 7 ft 4 in, so the smallest stock rug that covers it is 10 ft by 8 ft. Note that the dining rule is the one case where this tool rounds up rather than down: the pull-out is a minimum, and a 10 by 7 rug would leave the chairs 4 inches short on the long sides.
Two adjustments are worth knowing. If the table has leaves you insert for guests, size to the extended tabletop, not the everyday one. And if the table is round, the rug should be round or square rather than rectangular, at a diameter of the tabletop plus twice the pull-out, because a rectangle around a round table leaves the corner chairs unsupported while wasting rug at the corners.
Standard Sizes, and Why Your Exact Number Will Not Be One
Rugs come in a short list of sizes and the calculation rarely lands on one. The common rectangles are 3×5, 4×6, 5×8, 6×9, 7×10, 8×10, 9×12, 10×14 and 12×15 feet, with runners at about 2 ft 6 in wide in 8, 10 and 12 ft lengths, and round rugs at 4, 6, 8 and 10 ft diameters. Metric markets use 120×170, 160×230, 200×290 and 250×350 cm, which are near but not equal to the imperial sizes.
This tool deliberately rounds down to the largest standard size that fits inside the exact figure, so the recommendation never exceeds the space the rule allowed. The grid then shows what margin you actually end up with, and that is the number to judge. A margin between roughly 8 and 24 inches looks intentional. Below about 6 inches the rug reads as failed wall-to-wall carpet. Above about 30 inches in a normal room, the rug starts to float and you want the next size up.
Break the standard-size rule when the room suits none of them, which happens most in long narrow spaces. Two smaller rugs defining two zones beat one compromise rug, and a runner is the right answer in a hallway. Where nothing stock works, a rug cut and bound from broadloom is an option, and the carpet calculator sizes the drop it needs.
Pile, Fibre and the Things Size Does Not Tell You
Size is most of the job, but two other decisions interact with it. The first is pile height. A high pile in a dining room fights the chairs and traps everything that falls off a plate; a low flat weave is what makes the dining rule workable. Under a door, pile height decides whether the door still opens — measure the gap first, because a bound rug cannot be trimmed to fit.
The second is fibre, which decides how the rug wears in the position you just sized it for. A rug spanning a main traffic route is doing something quite different from one confined to a seating island, and fibre and construction matter more than price there. The University of Georgia Cooperative Extension textiles programme publishes independent guidance on fibre properties, selection and care that is not written by anyone trying to sell a rug. A pad or underlay is the last item: it adds a few millimetres of height, extends the rug’s life, and stops it travelling across a hard floor.
Arb Digital sizes campaigns the way this page sizes a room — take the real dimensions first, then choose from what actually exists.
Browse All Free Tools Talk To Our TeamCommon Mistakes to Avoid
- Buying one size down to save money — the single most common error. A too-small rug makes the whole room read smaller and cannot be fixed by anything else you put in it.
- Sizing a dining rug to the tabletop — without the pull-out allowance on all four sides, chair legs drop off the edge every time someone stands up.
- Measuring the sofa instead of the group — the seating rules apply to the rectangle containing every piece, including the armchairs and the coffee table.
- Assuming metric and imperial sizes match — a 200×300 cm rug is roughly 6 ft 7 in by 9 ft 10 in, not 6×9 or 8×10.
- Forgetting the door swing — pile height plus underlay can exceed the gap under an inward-opening door, and a bound rug cannot be trimmed afterwards.
Related Free Tools From Arb Digital
Size a wall-to-wall installation with the carpet calculator, plan boards with the flooring calculator, measure an awkward plan with the square footage calculator, work out tile quantities with the tile calculator, switch between square feet and square metres with the area converter, or size the linen for the table the rug sits under with the tablecloth size calculator. The full free online tools hub lists every home and everyday calculator we publish.
Frequently Asked Questions
Subtract twice your desired bare floor margin from each room dimension, then buy the largest standard rug that fits inside the result. In a 14 by 12 foot room with an 18 inch margin that gives 11 by 9 feet, so a 10 by 8 rug is the size to buy.
They can be, and it looks generous, but it needs a large rug. Front legs on is the usual compromise: the rug tucks a short way under the front legs of the sofa and chairs, which ties the group together without paying for the full footprint.
At least the chair pull-out distance beyond every edge, which is usually 24 inches. A 72 by 40 inch table therefore needs about 120 by 88 inches of rug so the chairs stay fully supported when pushed back.
Roughly 8 to 24 inches on each side. Under about 6 inches the rug reads as badly fitted carpet, and much over 30 inches in a normal room it starts to float and would be better one size up.
Yes, most obviously under a round table, in a square room, or in an entry where a rectangle would fight the door swing. The diameter is worked out the same way, using the shorter of the two dimensions the rule produces.
No. A 200 by 300 centimetre rug is about 6 feet 7 inches by 9 feet 10 inches, which is between a 6 by 9 and an 8 by 10. Always convert before comparing, because an inch is exactly 25.4 millimetres.
One rug sized to the whole room usually looks stretched. Two smaller rugs defining separate zones, or a runner where the space is genuinely a passage, will normally work better than a single compromise size.
This page describes standard interior furnishing conventions for general information only. Measure your own room and furniture before ordering, and confirm dimensions with the retailer, as rug sizes are nominal and finished pieces vary by an inch or two.
