How to use the furniture fit calculator
- Pick the piece and type its size. Width, depth and height at the widest points, with the legs off if they come off. For a sofa, tick Use its shape and add the arm height and the depth of the back: the arms are lower than the back, and that is what lets a sofa tip through a door it couldn't pass standing up.
- Add the way in, in order. Every doorway, hallway corner and flight of stairs between the truck and the room. For a door off a hallway, choose Turning in from a hallway and give the hallway's width: turning in is often harder than the door itself.
- Read the verdict and watch it. The result names the tightest spot, the room to spare there and the way to carry the piece (upright, on its back, on its end or tipped at an angle). The 3D view plays the move; Tightest stops at the pinch point, and Drawing shows it flat from above, from the side or from the front.
Measuring the door and the stairs
The number that matters for a door is its clear width: open the door fully and measure from the door stop on the latch side to the face of the door. The open door and its stops take a few inches out of the frame, so a door sold as 36 inches wide gives less than 36 inches of room. This is the same way building codes measure it: the International Residential Code asks for at least one main door with 32 inches (813 mm) of clear width, measured between the face of the door and the stop with the door open 90 degrees, and 78 inches (1981 mm) of clear height; other doors in a house can be narrower. Taking the door off its hinges gives back about its own thickness.
For stairs, measure the narrowest width where the piece will pass (usually between the handrails), and the headroom: straight up from the front edge of a step to the lowest thing above it, usually the edge of the floor above near the bottom of the flight. Add the step height and depth and the number of steps, and whether the stairs turn at a landing.
How the check works
A doorway taken straight on is exact geometry: the piece goes through in a straight line, so it fits when its outline, seen along the way it travels, fits inside the opening. The calculator tries every way round and every tilt, half a degree at a time, and keeps the one with the most room. That tilted outline is where the famous diagonal depth of a sofa comes from.
Corners, turning into a door and landings need a motion, not just a shape. The calculator carries the piece at a fixed tilt no taller than the ceiling, and a motion planner searches every position and angle for a route from one side to the other, then checks the route in steps of a few millimetres and measures the gap along it. Standing a long piece on its end often gets it round a corner that it can't turn lying down, but tipping it up takes more height than it has standing: a sofa 84 inches long and 33 high passes through about 90 inches on the way, its side's diagonal. The calculator only offers a way of carrying it that it can be tipped into under that step's ceiling. On stairs, the piece is carried at a fixed width across the stairs and turned in the side view, between the steps and the ceiling, from the floor below to the floor above. At a landing it turns as it arrived from the flight, and any part that swings out over the next flight's steps has to be lifted over them.
The room to spare is the distance between the piece and the nearest wall, frame, step or ceiling at the tightest moment, with the piece held in the best spot. Results within about a quarter of an inch (half a centimetre) either way are shown as too close to call: tape measures, carpets and bulging cushions make that much difference. For corners, turns and stairs the band reaches a little further on the short side, because the planner's search can miss the very best route by a few millimetres. Within the assumptions below, a "fits" comes with a real movement the calculator has checked; where your home differs from them, it can be tighter than the answer.
What the model assumes
- The piece is rigid: a box, or for a sofa two boxes (the seat with its arms, and the taller back). Soft cushions, removable legs and feet, doors that come off and mattresses that bend can only make things easier than the answer.
- Walls are straight and upright, floors and ceilings are flat, and doorways are rectangles. Hallways run on for longer than the piece before and after a corner.
- Each step starts with the piece standing as it normally does. Around corners and on landings it keeps one tilt all the way; people sometimes tip and turn at the same time, which the check doesn't try.
- A flight of stairs has open floor at the bottom and at the top. If the stairs start or end in a hallway or at a door, add that corner or doorway as its own step. With a landing, the flight after it isn't checked: add it as another stairs step if it is narrower or lower.
- "Keep it upright" lets the piece lean up to 45°, as on an appliance dolly. That limit is this calculator's choice, not a maker's figure: check your appliance's instructions.
- Nothing about handrails, light fittings, radiators or door handles: measure the width where they are, or subtract them.
Tips when it doesn't fit
- Take the legs off, and the door off its hinges; for a fridge, check the maker's depth without the doors.
- Try the piece on its end at corners and landings, and tipped back through doors: the calculator already tries these, and the result says which one works.
- Check a different way in: another door, a patio door, or a wider window on the ground floor.
- Planning where it will go once it's in? Lay the room out in the 3D room planner, which this calculator can take door sizes from. Painting first? The paint calculator and the flooring calculator work out what to buy.
Sources, checked September 2026: International Residential Code 2021, section R311.2, egress door (via UpCodes); U.S. Access Board, 2010 ADA Standards, 404.2.3 clear width (32 inches, measured between the face of the door and the stop with the door open 90 degrees); JB Kind, standard door sizes (UK internal doors, most commonly 762 × 1981 mm and 35 mm thick); Framewell, clear opening width of a 36-inch door (about 33 inches on a typical home door, used for doors taken from the Room planner).