I’ve used this chart to better visualize how much I can crop a higher resolution frame in post and still stay at 1080P natively. It can also help in planning shots and digital pans.
In a pinch you can crop/zoom in on 1080 in your editing software a little bit more and still deliver HD with no one noticing if you start with a nice sharp image that’s well-exposed or are using some weird filters throughout. I prefer the no filter version, since other video magicians can see through the flashy tricks.
I found it at http://abekislevitz.com/understanding-your-new-gopro/ which is why it shows all the resolutions a Go Pro provides. It’s a useful site though it’s not particularly active now; I found the older posts useful when I was getting a handle on mine.
P.S. Not an actual handle. Not like this one: