Measure the Furniture
Record the dimensions of the item as it will actually travel, not only how it looks when assembled.
Buying flat-pack or furniture in cartons?
Ask the seller: "What is the length, width and thickness of the largest piece that will actually be delivered?" For beds and similar furniture, the longest carton often determines whether the route works.
Buying second-hand, for example on Dubizzle?
Ask the seller for a photo showing a tape measure against the item. Listed dimensions are often estimates.
Which sides have to pass through a door?
A door only needs to clear two of the item's three dimensions because you can change its position as it passes through. For sofas and chairs, check the door width against the item's depth, diagonal depth or height, then check the door height against the remaining dimension.