1:1 vs 4:5 vs 9:16: which aspect ratio for which platform

Use 9:16 for TikTok, Reels, YouTube Shorts, and any placement that plays full-screen by default; use 4:5 for the Instagram and Facebook in-feed experience and for LinkedIn; use 1:1 when a clip has to work identically across many placements or is built around a shared screen or slide.

The reason 9:16 isn't universal: on a scrolling feed (Instagram main feed, LinkedIn, Facebook), a true 9:16 video gets letterboxed or cropped in the preview, wasting the top and bottom. A 4:5 video fills the maximum allowed feed height without going full-screen, so more of the frame is actually visible while someone scrolls.

1:1 square is the safe default for repurposed screen-share content — a demo, a spreadsheet, a slide. Cropping that to 9:16 usually destroys the readable content; a square keeps the shared material legible with room for a caption strip.

There's also a production cost angle. If you shoot or record once and know you'll post to five places, framing your subject with padding on the sides lets you export 9:16, 4:5, and 1:1 from the same source without re-shooting. Frame for the widest crop you'll need.

Text placement changes per ratio. Captions and titles that sit comfortably in a 9:16 safe zone can collide with platform UI in a 4:5 export. Check each ratio's export, don't assume the 9:16 layout transfers.

Practical rule: make 9:16 your primary, export 4:5 for the feed-based platforms, and only add 1:1 when the clip contains screen-share or slide content that a vertical crop would ruin.

OptimaClip exports all three ratios from one project with the caption position adjusted per ratio, so you're choosing placements rather than re-editing.