Measure the path, not just the wall

People tape the wall they want the sofa against and stop there. Delivery does not start at that wall. It starts at the street.

Walk the route with the tape: building door, stair turn, landing rail, the room door and the way it swings. Note the tightest clear width, not the average. A 78 cm landing with a radiator is the measurement that matters.

Sellers publish packed size as well as assembled size. The packed carton is often the one that will not rotate on the stair. If both numbers are on the product page, believe the larger one for the path.

In the studio you can test the assembled footprint. You still need five minutes in the stairwell with a tape. Those two checks answer different questions, and neither replaces the other.