What is a video aspect ratio?
The aspect ratio is the shape of the frame: width to height, written as two numbers (16:9) or one decimal (1.78:1). It says nothing about quality. 1280×720 and 3840×2160 are both 16:9; the second just has nine times as many pixels. When a platform gives a range like "1:2.4 to 2.4:1", any shape between the tallest and the widest is allowed.
What are the common video aspect ratios and sizes?
| Ratio | Decimal | What it is | Pixel sizes |
|---|---|---|---|
| 16:9 | 1.78 | Widescreen: HD, 4K, YouTube, most screens | 1280×720, 1920×1080, 2560×1440, 3840×2160 |
| 9:16 | 0.56 | Full-screen vertical: phones, Reels, Shorts | 720×1280, 1080×1920, 2160×3840 |
| 1:1 | 1.00 | Square: feed posts | 720×720, 1080×1080, 2160×2160 |
| 4:5 | 0.80 | Portrait: taller feed posts | 864×1080, 1080×1350, 2160×2700 |
| 4:3 | 1.33 | Classic TV and many tablets | 640×480, 1440×1080 |
| 2.39:1 | 2.39 | Cinema widescreen ("scope") | 1920×803, 3840×1607 (rounded) |
Pixel sizes are arithmetic (height = width × ratio height ÷ ratio width), not platform claims. 2.39:1 doesn't divide evenly, so its sizes are rounded.
Which aspect ratio does each platform accept?
| Platform | Stated rule | 16:9 | 9:16 | 1:1 | 4:5 | 2.39:1 |
|---|---|---|---|---|---|---|
| 1:2.4 to 2.4:1 (source) | Yes | Yes | Yes | Yes | Yes | |
| X (web upload) | 1:2.39 to 2.39:1; max 1920×1200 or 1200×1900 (source) | Yes | Yes, up to 1200×1900 | Yes | Yes | Yes |
| Instagram Reels | 1.91:1 to 9:16 (source) | Yes | Yes | Yes | Yes | No |
| YouTube | 16:9 standard; vertical and square accepted (source) | Yes | Yes | Yes | Yes | Not stated |
| YouTube Shorts | Square or vertical (source) | No | Yes | Yes | Yes | No |
| Any aspect ratio (source) | Yes | Yes | Yes | Yes | Yes | |
| Threads (API docs) | 0.01:1 to 10:1; 9:16 recommended (source) | Yes | Yes | Yes | Yes | Yes |
From each platform's own help page (Threads: Meta's Threads API documentation), checked November 4, 2026. "Yes" means the ratio is inside the platform's stated range; it isn't a recommendation. TikTok is left out: we couldn't open its organic help pages to verify.
Three things stand out. 1:1 and 4:5 fit everywhere. Shorts won't take landscape: YouTube describes Shorts as square or vertical. Instagram stops at 1.91:1, so a 2.39:1 cinematic cut won't fit a Reel. For the full limits per platform, see social media video sizes.
How do you calculate an aspect ratio?
- Find the greatest common divisor of the width and height. For 1920×1080 it's 120.
- Divide both by it. 1920 ÷ 120 = 16 and 1080 ÷ 120 = 9, so the ratio is 16:9.
- For a decimal, divide width by height: 1920 ÷ 1080 = 1.78, written 1.78:1.
To find a missing side, multiply across: height = width × (ratio height ÷ ratio width). A 1080-wide 4:5 video is 1080 × 5 ÷ 4 = 1350 tall. Odd sizes like 1366×768 don't reduce neatly (683:384), which is why they're usually described by the nearest common ratio, 16:9.
What aspect ratio should a launch video be?
Make the master 16:9 at 1920×1080: it's YouTube's standard, and Product Hunt takes only a YouTube link. Then cut a 9:16 (1080×1920) or 4:5 (1080×1350) version for Reels, Shorts and phone-first feeds, reframing the product UI rather than letterboxing it. The launch video guide covers length and structure, and each platform page has an export recipe: LinkedIn, X, Instagram Reels, YouTube, Shorts.