Then 3 zones is 1920x1136, but as Jen explains in her post, she uses 4 zones instead and edits it so that zone 4 is exactly the same as zone 1 and then it will loop more smoothly (of course, it’s up to you whether you want to do that or not).
1 zone = 640x1136.
2 zones = 1280x1136.
3 zones = 1920x1136.