Two halves: a split image for X that fits without a swipe
Two halves is the simplest split: one picture, two images side by side in the post. With exactly two, X lowers the row until both fit the width of the media column, which it does for three or more only when one strip takes 80% of it, so a landscape up to about 2:1 shows whole at a glance. The cut still leaves out the 6 px of border and gap between the halves, so the seam lines up.
Make it yours
Very wide pictures
If the picture is wider than about 2:1, X keeps the row at full height and the sides are cropped: use Crop position to keep the part that matters.
Halves for desktop
Choose Desktop in Match gaps for if the post is aimed at the desktop feed; the seam sits in the same place, but the 6 px X hides take a smaller share of a 490 px column.
FAQ
Why does X show two images lower than three?
X sizes a two-image row so both pictures fit side by side across the column, as long as enough of the second one shows. With three or more, it makes the row taller until the first strip and two thirds of the second fill the view, which for narrow strips means its full height.
How it works
Add a picture
Upload a picture or pick one from the gallery. A 4:5 or taller picture shows whole inside the feed; a wider one runs past its edge and invites a swipe.
Shape the row
Choose 2 to 20 strips, the row width and the feed to match the gaps for. Drag a strip's edge to widen it, drag the picture to move the crop, double-click an edge for equal strips.
Download and post
Sign in with a free UX Pilot account to download a ZIP with one PNG per strip, numbered in order, then add them all to one post in that order.