You shot a beautiful video, and then you posted it — and the platform turned it into a letterboxed mess with black bars on every side. Or worse: it cropped out the subject entirely. The aspect ratio, the shape of your video, decides how it fits into every platform's player, and getting it wrong is the most common self-inflicted video wound.

Here is what each ratio means, and which one each platform actually wants.

What an aspect ratio is

The ratio of width to height, expressed as width:height. 16:9 means the video is 16 units wide for every 9 units tall — widescreen. The numbers are simplified: 1920×1080 is 16:9, 1280×720 is 16:9, and so on.

The four ratios that matter

16:9 (landscape/widescreen)

The default of cameras, TVs, YouTube, and computer screens. 1920×1080 is the standard size.

**Use for:** YouTube, Vimeo, embedded videos on websites, presentations, TV playback, desktop viewing. If you don't know where a video will end up, shoot and share 16:9 — it is the universal fallback.

9:16 (vertical/portrait)

The phone-native format. Taller than wide, made for the way people hold their phones. 1080×1920 is the standard size.

**Use for:** TikTok, Instagram Reels, YouTube Shorts, Instagram Stories, Snapchat. The rule is simple: if the video is meant to be watched on a phone inside a full-screen feed, it belongs in 9:16.

**The mistake to avoid:** shooting horizontal and rotating. The frame doesn't rotate with you — shoot 9:16 natively or crop in post from a taller composition.

1:1 (square)

Exactly as wide as tall. 1080×1080 is the standard size.

**Use for:** Instagram feed posts (though Instagram now supports both orientations, square still looks most at-home), thumbnail crops, cross-posting where both orientations get shown. Square is the compromise format: acceptable in landscape feeds, acceptable in portrait feeds, perfect in neither.

4:3 (classic/retro)

The shape of old television and most DSLR video. 1440×1080 or 640×480 are common sizes.

**Use for:** Vintage aesthetic, some animation workflows, and little else in the modern share economy. Most platforms letterbox it into 16:9. Include it here because your camera might shoot it by default — switch to 16:9 unless you specifically want the look.

Platform cheat sheet (2026)

| Platform | Best ratio | Accepts | |---|---|---| | YouTube (standard) | 16:9 | Anything (letterboxed) | | YouTube Shorts | 9:16 | 9:16 only | | TikTok | 9:16 | 9:16 only | | Instagram Reels | 9:16 | 9:16 only | | Instagram feed | 4:5 or 1:1 | 1:1 to 4:5 | | Website embeds | 16:9 | 16:9 | | Chat apps | Any | Any (fills preview) |

How to convert between ratios

Crop (most common)

Cut off the sides to fit a taller ratio, or the top and bottom to fit a wider one. The trade: you lose content. Compose with the crop in mind — keep the subject centered with margin, or shoot twice as wide as needed.

Letterbox/pillarbox (safe)

Add black bars to fill the gap. No content lost, but the bars look unprofessional in feeds. Fine for archival and internal sharing; wrong for social.

Reframe with AI (newest)

Tools like CapCut and Premiere auto-reframe, tracking the subject as they crop. Works well for talking heads; struggles with fast action and multiple subjects.

The practical workflow

Shoot 16:9 as your master. For social derivatives, crop to 9:16 from the center or a tracked position, keeping the subject in the safe zone (the middle 80% of the frame). Export one master, derive per platform, and upload each derivative where it belongs — or use a platform that serves the correct rendition automatically.

The takeaway

16:9 for the desktop world, 9:16 for the phone-feed world, 1:1 when you need one file for both, and 4:3 only by choice. Match the ratio before you edit, not after you upload.