What's the maximum necessary size in pixels for a video for iPhone? I'm exporting MOVs from Flash, then converting them to mp4 with Handbrake. The video will scale to the screen size, but I would prefer it to scale down, rather than  scale up. 

So, what are the optimum pixel width and height of a MOV/mp4 for iPhones? By "optimum", I mean the maximum needed to display 1:1 on the highest definition iPhone screen. 

I know iPhone screen sizes have changed with each new iPhone, and screen sizes come in points, rendered pixels, physical pixels and physical devices. But hopefully in the end there's max X-px x Y-px.
The currently biggest iPhone is the iPhone 7 plus. It has a 5.5-inch (diagonal) LED-backlit widescreen.


In landscape mode it has a 1920-by-1080-pixel resolution at 401 ppi.
In portrait mode it has a 1080-by-1920-pixel resolution at 401 ppi.


Which is the equivalent of a full HD movie.