Naturally, double strollers are a lot wider than single strollers when they’re in a side-by-side configuration.
The answer to this question actually largely depends on where you live. In the US, the typical door is around 91cm (36”) wide. The widest stroller on this list is 80cm (31.5”), so you know you’re generally going to be pretty safe. If you’re in the UK, however, it’s a very different story. The average front door is 78cm (31”) in the UK, so some of these double strollers simply won’t fit through the door.
You probably want to give yourself at least 5cm (2”) of room either side to make sure you can fit the stroller through without issue.