9:16, 1:1 or 16:9: which ratio for which platform

Most source footage is 16:9, because that is what cameras and recording software produce. Most short-form feeds want 9:16. The gap between those two facts is where a lot of clips get ruined.

What each ratio is for

• 9:16 is the full-screen vertical feed: TikTok, Reels, YouTube Shorts. It fills a phone screen and gets the most attention, and it throws away roughly two thirds of a 16:9 frame.
• 1:1 is the square. It was the Instagram feed standard for years and still works well in a scrolling timeline, on LinkedIn, and anywhere the video sits inline rather than full-screen.
• 16:9 is the original shape. Keep it for YouTube proper, for embedding on a site, and for anything where the whole frame carries information.

The question is what you are cropping away

A single speaker centred in frame crops to 9:16 almost for free. A two-person interview shot wide does not — the vertical crop either cuts both people in half or picks one and loses the other. A screen share, a slide, a whiteboard or any footage where the information is spread across the frame usually cannot survive a vertical crop at all.

So the practical rule is not per platform, it is per shot. Ask what is in the parts of the frame you are about to delete. If the answer is a wall, crop freely. If the answer is the other half of the conversation, you need a tool that moves the crop rather than fixing it.

When square is the better answer

Square is underrated for talking-head content with two people. It keeps enough width to hold both faces without the extreme crop that vertical demands, and it still reads well on a phone. If a clip refuses to work in 9:16, try 1:1 before you give up on it.

Do not letterbox

Putting a 16:9 video in a 9:16 canvas with black bars top and bottom is technically vertical and practically a waste. You get a small picture in the middle of a phone screen, surrounded by nothing, competing against clips that fill the frame. If the footage cannot be cropped, post it in its own ratio somewhere that suits it.

Where the captions go

The ratio also decides how much room captions have. In 9:16 there is vertical space to spare, which is why burned-in captions became standard there. In 16:9 the same caption size covers a meaningful part of the picture. Size the captions for the shape rather than carrying one setting across all three.

Picking once versus picking per clip

It is tempting to set one ratio and forget it. In practice the best output comes from choosing per clip, based on what is in the shot — which is why Keptbits asks each run rather than remembering a default, and why re-exporting a clip you already have in a different ratio does not cost anything.