How Much Fabric to Reupholster a Sofa?
A sofa is the biggest fabric purchase most people ever make, and the number is always higher than it looks like it should be. The reason is that you are pricing the parts you can see, and most of the cloth goes somewhere else.
Most of It Goes Where You Never See It
Stand in front of a sofa and you see the outside back, the outside arms, the front of the cushions and the arm fronts. That is maybe a third of the fabric in the piece.
The rest is hidden. There is a deck, the platform under the seat cushions, which is a large panel nobody ever looks at. There are two inside arms, which are bigger than the outside arms because they curve over and down. There is an inside back that carries on past where you can see it and gets tucked into the frame. And the fabric wraps round the bottom rails and staples underneath, which sounds trivial until you count the perimeter of a sofa.
This is why an estimate based on the visible surfaces comes out around half of what the job needs, and why the tear-down stage so often produces a second trip to the shop.
A Three Seat Sofa, by the Numbers
Put a typical three seater, 84 inches wide by 38 deep by 36 high, through the upholstery calculator and it reports 18.75 yards. For comparison, the same model puts an armchair at 9.5 yards.
So a three seat sofa is roughly two armchairs, which is a useful sanity check to carry around. If someone quotes you eight yards for a full sofa recover, something has been left off the list.
At that scale, fabric price stops being a detail. Ten pounds or dollars a yard between two cloths you like is nearly two hundred on the finished job, which is often the difference between two entirely different fabrics being affordable.
Railroading: Turning the Cloth Sideways
Here is the trick that separates people who have done this from people who have not. A sofa back is 84 inches wide. Your fabric is 54. Run the cloth the normal way, with its length going up and down the sofa, and that back panel needs two pieces joined with a seam straight across the middle of the most visible surface in the room.
Railroading means turning the fabric ninety degrees so its length runs sideways across the sofa instead. Now the 54 inch width becomes your height, which is plenty for a 36 inch back, and the length of the roll runs the full 84 inches with no seam at all.
It only works if the fabric lets you. A plain cloth or a random texture railroads happily. A one way nap, a directional print, or a stripe that must run vertically does not, because turning it puts the pattern on its side. Many upholstery fabrics are woven specifically to be railroaded, with the pattern already running along the roll rather than across it, so it is worth asking before you choose.
When it works it saves a seam, and sometimes saves yardage too. When it does not, plan where the join will fall rather than letting it land wherever the cloth runs out.
Loose Cushions Are Their Own Job
Seat and back cushions that lift out are separate covers with their own tops, bottoms, boxing strips and zips. Work them out in the cushion calculator rather than assuming they are folded into the frame figure, and put the whole set in at once, since identical cushions nest together and cost less as a batch than one at a time.
If you are not recovering the frame at all and just want the sofa to look different, a slipcover is a different calculation with its own tuck allowances and hems, and it can be taken off and washed.