One helpful guideline is to think of a scene as being continuous in time and place (and perhaps in POV). So if your characters are in one place and they go to another, and your narrative continues with them, that can be a single scene. But if your characters are in one place, and then you jump (discontinuously) to another time or place, the jump would start a new scene.
That said, this is just a guideline. Some writers make leaps of time or place within a paragraph. Others sometimes begin a new scene even when the time, place, and POV are continuous. Stephen King has been known to begin a new scene in the middle of a sentence (e.g. in a scene in Dreamcatcher as a character awakes from a dream).
But I find it a mostly helpful guide. When time, place, or POV jumps, start a new scene.