Layout Validator
Upload a finished post image and check it against Threads' UI overlay zones.
Anything in the dimmed area risks being covered by platform UI (titles, captions, buttons, rounded corners). Keep key subjects and text inside the dashed line.
Why two feed formats instead of one
Portrait 4:5 is Threads' own recommended default — it takes up noticeably more of the mobile feed than a square crop and tends to drive more engagement as a result. Square 1:1 is still fully supported and worth checking separately, since a design built for one aspect ratio rarely centers correctly if it's just stretched into the other.
What's actually at risk
Threads renders attached images with its own caption placement and action-button layout sitting below the image rather than on top of it, so a caption that runs long is the main thing that can push important context below what's visible before someone taps to expand — there's comparatively little UI actually layered over the image itself on either format.
The profile format is excluded here since the picture/bio overlap it involves is already covered by the dedicated Threads Profile Preview tool.