// GLOSSARY · ASPECT RATIO

Aspect ratio

The proportional relationship of a video or image’s width to its height, expressed as W:H (e.g. 9:16, 1:1, 16:9).

Last verified · 2026-10-23 · by Moe Ameen

Published 2026-05-22 · Updated

Short answer

Aspect ratio is the width of an image or video compared to its height, written W:H. The four that matter most for social content are 9:16 vertical, 1:1 square, 4:5 portrait and 16:9 horizontal. Meta recommends 4:5 for Instagram feed images and 9:16 for Reels and Stories, TikTok recommends 9:16, and YouTube's standard player ratio on desktop is 16:9.

Key takeaways

  • Aspect ratio is width to height, written W:H.
  • Meta recommends 4:5 for Instagram feed images and 9:16 for Reels and Stories.
  • TikTok recommends 9:16 vertical; YouTube's standard desktop ratio is 16:9.
  • A mismatched ratio gets letterboxed or cropped, so render each version natively.

What does aspect ratio mean for social video?

Aspect ratio determines how an image or video fits inside a platform's feed slot. The four ratios that matter for content creators: 9:16 (vertical, Reels/Shorts/TikTok/Stories), 1:1 (square, Instagram feed legacy), 4:5 (portrait, Instagram feed current), 16:9 (horizontal, YouTube/desktop).

Each platform has a preferred ratio and a range it tolerates. Meta's ads guide accepts Instagram feed images anywhere from 1.91:1 (landscape) to 4:5 (portrait) and recommends 4:5, the tallest option, so it takes up the most room on a phone screen. For Instagram Reels, Meta recommends 9:16.

Mismatched aspect ratios get letterboxed (black bars) or auto-cropped (subject offscreen). Either signals "lazy cross-post" to the algorithm and to viewers. Kompozy renders each output at the destination platform's native ratio per the persona's outlet config.

What does this look like in Kompozy?

A real image post from the Kompozy workspace, rendered at a fixed feed ratio. It shows the kind of platform-sized image Kompozy produces.

Infographic photo post generated in Kompozy
Real output · Kompozy Infographic photo format · from the Kompozy workspace

Who is this for, and who should skip it?

Best for:

  • Creators posting the same idea to several platforms with different feed shapes
  • Anyone tired of black bars or cropped faces on cross-posts

Not ideal for:

  • Single-platform creators who already shoot in that platform's native ratio
  • Print or broadcast work, which follows different specs

Frequently asked questions

What is aspect ratio?

Aspect ratio is the proportional relationship of a video or image's width to its height, expressed as W:H — for example 9:16, 1:1, or 16:9. It determines how an image or video fits inside a platform's feed slot.

Which aspect ratios matter most for content creators?

Four ratios matter: 9:16 (vertical, for Reels, Shorts, TikTok, and Stories), 1:1 (square, legacy Instagram feed), 4:5 (portrait, current Instagram feed), and 16:9 (horizontal, YouTube and desktop).

Which aspect ratio works best in the Instagram feed?

Meta recommends 4:5 for Instagram feed images. It is the tallest ratio the feed accepts, so it fills the most screen space. For Reels, Meta recommends 9:16.

What happens when an aspect ratio doesn't match the platform?

Mismatched aspect ratios get letterboxed with black bars or auto-cropped so the subject is offscreen. Either one signals a lazy cross-post to the algorithm and to viewers.

How does Kompozy handle aspect ratios?

Kompozy renders each output at the destination platform's native ratio according to the persona's outlet config, so videos and images arrive sized correctly for each feed.

How do we know this?

We checked every figure and product claim on this page against the sources listed below on 2026-10-23, and removed or rewrote anything we could not confirm. Platform ratio guidance was read off Meta's ads guide, TikTok's ad specs and YouTube Help.

Sources

  1. Meta Ads Guide — Instagram Feed image ads (read 2026-10-23)
  2. Meta Ads Guide — Instagram Reels video ads (read 2026-10-23)
  3. Meta Ads Guide — Instagram Stories video ads (read 2026-10-23)
  4. TikTok Ads Manager — Video ads specifications (read 2026-10-23)
  5. YouTube Help — Video resolution & aspect ratios (read 2026-10-23)
  6. Kompozy — HyperFrames template gallery (read 2026-10-23)

Related terms

  • 9:16 video — Vertical video aspect ratio (1080×1920) — the native format for Reels, Shorts, TikTok, and Stories.
  • 1:1 video — Square video aspect ratio (1080×1080) — the legacy Instagram feed format, still useful for cross-posting across many platforms.
  • 4:5 video — Portrait video aspect ratio (1080×1350) — the current preferred format for Instagram and Facebook feed (non-Reels) posts.
  • 16:9 video — Horizontal widescreen aspect ratio (1920×1080) — the standard for YouTube, webinars, and desktop-first viewing.
  • Vertical video — Video shot or cropped at 9:16 aspect ratio, optimized for phone-held viewing on Reels, Shorts, TikTok, and Stories.
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