Aspect ratio
Also called 16:9, 9:16, 4:5, 1:1, video aspect ratio, image aspect ratio
What is an aspect ratio?
Aspect ratio is the proportional relationship between the width and height of an image or video, written as two numbers separated by a colon. 16:9 is widescreen, 9:16 is full-screen vertical, 1:1 is square and 4:5 is a tall portrait post. It describes shape only, not size or sharpness.
The same ratio can come at many pixel sizes. A 1920 x 1080 video and a 3840 x 2160 video are both 16:9; the second simply has a higher resolution. To find a ratio, divide both dimensions by their greatest common divisor: 1080 x 1350 reduces to 4:5.
Each placement has a preferred shape. YouTube and websites default to 16:9. Vertical video for Reels, TikTok, Shorts and Stories uses 9:16. Feed posts on Instagram, Facebook and LinkedIn work at 1:1 or 4:5, and link previews and many ads use about 1.91:1. Platforms adjust these from time to time, so check current guidance before a big campaign.
Why an aspect ratio matters
The wrong shape costs attention. A 16:9 video posted to Reels shows up as a thin strip with black bars, while a 9:16 video fills the phone screen. Taller formats take up more of the feed, which gives a post more time to catch someone mid-scroll.
Aspect ratio also decides what gets cropped. If you design for one shape and a platform shows another, text and logos near the edges can be cut off. Planning the ratio first, and keeping key content inside the safe zone, avoids that.
How to choose the right aspect ratio
- List where the piece will run: feed, Stories, Reels, YouTube, a website or an ad placement.
- Use 9:16 for full-screen vertical placements, 4:5 or 1:1 for feed posts and 16:9 for YouTube and web players.
- If one asset must serve several places, design the scene so the important parts sit in the center and survive cropping.
- Export a separate file for each ratio instead of letting the platform crop for you.
- Preview each version on a phone before posting.
Aspect ratio example
16:9 1920 x 1080 YouTube, websites
9:16 1080 x 1920 Reels, TikTok, Shorts, Stories
4:5 1080 x 1350 Instagram feed (portrait)
1:1 1080 x 1080 Instagram, Facebook, LinkedIn feed
1.91:1 1200 x 628 link previews, many adsAspect ratio FAQ
What aspect ratio is 1920 x 1080?
1920 x 1080 is 16:9, the standard widescreen ratio used by YouTube, TVs and most web video players.
What is the best aspect ratio for Instagram?
For Reels and Stories, 9:16. For feed photos and carousels, 4:5 takes the most space in the feed, and 1:1 is the safe square option. Instagram has changed its grid preview shape before, so check how covers crop on your profile.
Is aspect ratio the same as resolution?
No. Aspect ratio is the shape (16:9). Resolution is the number of pixels (1920 x 1080). Many resolutions share one ratio.
Related terms
Video resolution is the number of pixels in each frame, written as width x height or a shorthand like 1080p or 4K. More pixels means more detail.
Vertical video is video taller than it is wide, usually 9:16 at 1080x1920 pixels, made to fill a phone screen on Reels, TikTok, Shorts and Stories.
A safe zone is the area of a video or image where text and key content will not be hidden by platform buttons, captions or cropping.
Social media image sizes are the pixel dimensions and aspect ratios each platform recommends for posts, stories, ads, profile banners and link previews.
The Instagram post size is 1080 px wide, at 1080×1080 (square), 1080×1350 (portrait 4:5) or 1080×1440 (3:4); portrait fills the most screen.