The sofa that wouldn't go in

Most sofa regrets are not about colour. They are about the moment two people stand in the hallway, holding a sofa that is a few centimetres too big for the door. Whether it gets in has very little to do with how long the sofa is. What matters is its cross-section: the outline you would see if you sliced it across and looked at the end. The sofa goes through the doorway like a long loaf through a letterbox, end first.

Below, put in your sofa's measurements and your doorway, then turn the sofa to see what the opening allows.

Why the cross-section decides

A rectangle that is taller than the gap is wider than it looks once you tilt it. Turn a sofa's end view inside a doorway and its overall footprint changes: the diagonal of a rectangle is longer than either side. That is why the slider above matters. A sofa that is 92 cm deep and 85 cm tall cannot pass a 78 cm gap upright, and no twist helps, because its smallest dimension is already 85 cm.

The useful fact is this: a sofa can only pass a gap if two of its three measurements are small enough to slip through, at some angle. The third, usually the length, can be as long as you like, as long as there is room to swing it in the hall.

Try the default numbers, then tick "Legs unscrewed". The sofa loses 12 cm of height and goes from stuck to through. Many sofas have legs that screw out, and arms or backs that detach with a few bolts. Check the maker's page before you order.

What to measure

• The sofa: length, depth and height, with and without legs, from the product page. Sofa pages usually list these. If a piece arrives in a box, the box size is the one that counts.
• The doorway: the clear width between the frame stops, not the width of the door. A door open at 90° eats a few centimetres; taking it off its hinges often gives some back. Measure the clear height too, usually the easy part.
• The route: the front door, the hall, any stairs, any lift. Each narrow point is its own doorway. Measure the narrowest, and note where there is a turn, because turns are where sofas get stuck.
• Whoever carries it: a shop's delivery team can often take the legs off and handle the turns, so ask what the service includes.

Interior door leaves differ by country, and clear openings are smaller than the leaf. So do not guess from "standard" door sizes; a tape measure takes a minute.

When the numbers say no

You have more options than buying a smaller sofa. A modular or sectional sofa arrives in pieces and is built in the room. Some sofas have flat-pack frames. Second-hand sofas are worth a look too, since you can ask the seller for exact measurements and whether it is easy to take apart. If the front door is the problem and you live on a higher floor, ask a delivery company whether they can lift through a window, a job for professionals.

And if your current sofa is the one that does not fit anywhere you want it, rearranging the room you have is often cheaper than replacing it. Free options first, always.

Break the rule of thumb

This planner treats the sofa as rigid. Real sofas squash a little: cushions compress and soft arms bend. That can buy a centimetre or two, but do not plan around it. Heavy, hard-framed sofas do not give at all. When the result says "spare room: 0.5 cm", treat that as a no.