Measure the furniture relationship before choosing the rug label.
This calculator starts with the part of the seating arrangement the rug must connect. It adds the same user-chosen border to all four sides, producing a target rectangle instead of guessing from a room label. That keeps the calculation tied to the sofa, chairs, and table that will actually touch or sit within the rug perimeter.
The result also names the first common catalog size in the selected measurement system that meets or exceeds both target dimensions. It does not call that size perfect. Rug dimensions differ between sellers, and a larger catalog rectangle can conflict with a doorway, floor vent, circulation path, or an angled chair. Treat the comparison as a shopping filter, then test the exact product dimensions on the floor.
Worked example
A 276 cm seating span with a 20 cm border
A sofa and two angled chairs create a 276 cm wide by 190 cm deep contact rectangle. The plan calls for 20 cm of visible rug beyond that measured relationship on every side.
Seating group
276 x 190 cm
Border on each side
20 cm
Calculated target
316 x 230 cm
How RoomFact reads it
The target is 316 x 230 cm. In the metric comparison list, 200 x 300 cm is smaller than the target in both directions, while 240 x 340 cm is the first listed size that covers it when rotated to suit the seating group.
A 200 x 300 cm rug would remove 30 cm from the target depth and 16 cm from its width. That changes the intended furniture relationship rather than merely trimming an invisible allowance.
A nominal 240 x 340 cm option provides about 10 cm of extra depth and 24 cm of extra width overall. Centering it would split that surplus between opposite sides, but the actual product dimensions still control.
The larger candidate remains provisional until its full outline is taped around the real furniture, with the nearby doorway and primary walking path in use.
01
Decide which furniture points the rug must connect
Choose the layout before taking dimensions. For an all-legs-on arrangement, mark the outermost foot of every sofa and chair that should sit on the rug. For a front-legs-on arrangement, mark the front feet and the outside width of the complete conversation group. A coffee-table-only rug uses a different, smaller relationship and should be an intentional choice rather than the accidental result of buying by room name.
Angled chairs and sectional chaises often set the true width or depth. Put small pieces of painter tape under the intended contact points, then measure the smallest rectangle that contains them. Do not measure soft cushions, wall-to-wall room dimensions, or an empty area that the furniture never reaches. The calculator is only as useful as that contact rectangle.
02
Use the border as a design decision, not a universal rule
The border input is the amount of rug you want beyond the measured contact rectangle on each side. A wider border can make the rug feel more deliberate and protect against small placement changes, but it also increases the chance of entering a doorway arc or circulation route. RoomFact does not insert a supposedly ideal border because furniture scale, room shape, and product availability vary too much for one number to be honest.
Run more than one border value and write down how the target changes. A 5 cm increase on every side adds 10 cm to both finished dimensions. Compare those targets with exact product listings, not only labels such as medium, large, 8 x 10, or 200 x 300. Two sellers can use the same familiar label for dimensions that are not identical.
03
Test the product rectangle under normal room use
Tape the exact width and length from the product page, including the orientation you intend to use. Open nearby doors, pull chairs to their normal positions, walk the main route, and check whether anyone repeatedly steps with one foot on the rug and one on the finished floor. A rug that mathematically covers the furniture points can still create an awkward edge in daily movement.
Account for pile and the rug pad as well as footprint. Thick edges may affect a low door, chair movement, robot vacuum access, or a person with limited mobility. Confirm that the rug and pad are suitable for the finished floor and follow their care and safety instructions. The final purchase decision belongs to the exact product and room conditions, not the catalog comparison alone.