Will the couch fit through the door? 3 numbers to check

A couch fits through a door when its diagonal depth, measured from the top of the back to the bottom of the front, is less than the door's clear opening. Most US apartment doors give 29 to 34 in clear, and most sofas have a diagonal depth of roughly 30 to 38 in, so the door is rarely the problem. The hallway turn, the stairwell or the elevator is. Check all three before you order, because many stores do not take back a sofa that did not fit.

Number 1: the door's clear width

Open the door as far as it goes and measure from the door stop on the frame to the face of the door. A 32 in door slab gives about 30 in clear; a 30 in slab about 28 in; a 36 in slab about 34 in. Taking the door off its hinges adds 1 to 2 in. Measure the front door, the apartment door and the door of the room the sofa ends up in; the smallest number is the one that counts.

Number 2: the couch's diagonal depth

Sofas go through doors end first, tilted, so the measurement that matters is not the depth or the height but the diagonal of the end profile: from the top back corner of the frame to the bottom front corner (under the seat, not the cushion). It is almost always smaller than the height plus depth suggest because the back is thin. Two shortcuts:

• If the sofa's height is less than the door's clear width, it goes through on its side with no tricks. A 31 in tall sofa through a 32 in door.
• If the sofa's depth is less than the door's clear width, it goes through standing on its end. A 34 in deep sofa through a 36 in door.
• Legs that unscrew take 4 to 7 in off the height. Check the product page: IKEA, Article and most Wayfair sofas ship with the legs off.

Number 3: the tightest point of the route

Walk the route with a tape: building door, lobby, elevator, stairs, hallway, apartment door, the turn into the room. Write down the narrowest width and, for every 90 degree turn, the width of both hallways. A sofa turns a corner when it can stand on its end and pivot, which needs the hallway to be wider than the sofa's depth and a ceiling higher than the sofa's length. In a 36 in hallway with an 8 ft ceiling, an 84 in sofa 34 in deep turns the corner on its end; a 96 in sofa 40 in deep does not.

• Elevator: measure the door opening and the inside of the cab, corner to corner on the diagonal. Many cabs take an 84 in sofa on the diagonal and not a 96 in one.
• Stairs: the landing is the limit, not the stairs. Measure the landing's width and the headroom over the turn.
• Flat-pack sofas skip all of this. KIVIK, UPPLAND and most IKEA sofas arrive in boxes under 40 in; sectionals come in modules.

If it is an inch short

1. Take the door off its hinges (two minutes with a screwdriver and a hammer on the hinge pins).
2. Take off the legs, the cushions and any loose back pillows.
3. Stand the sofa on its end and bring it in back first, then tilt it through the frame.
4. Ask the store for the packaged size. A sofa in its box is often tighter than out of it; a sofa shipped in two pieces (seat and back) is far smaller.

Then check that it fits the room

Getting it in is half the question. The 12x12 living room guide gives the sofa width for each room size, and Fits Here shows the sofa in a photo of your room at real size, with the space left on each side.