PostEaseThe short answer
An aspect ratio is the shape of an image or video: its width against its height, written as two numbers. 16:9 is wide, the shape of a TV or a YouTube video; 9:16 is the same shape turned upright, the full phone screen that Reels, TikTok and Shorts fill; 1:1 is square.
The ratio says nothing about size. 1920 × 1080 and 3840 × 2160 are both 16:9; one has more pixels. What matters on social media is that the shape matches where the post will be seen, because a mismatched shape gets cropped or framed with bars.
The common ratios
Five shapes cover almost every post, each with a size taken from this blog’s platform specs:
| Ratio | Example size | Shape | Used for |
|---|---|---|---|
| 9:16 | 1080 × 1920 | Tall, full screen | Reels, TikTok, Shorts, Stories |
| 4:5 | 1080 × 1350 | Portrait | Instagram and Facebook feed posts |
| 1:1 | 1080 × 1080 | Square | Feed posts on most platforms |
| 2:3 | 1000 × 1500 | Tall portrait | Pinterest Pins |
| 16:9 | 1920 × 1080 | Wide | YouTube videos and link previews |
The shape each platform takes
The video shapes each platform accepts, as this blog’s specs posts give them from each platform’s own documentation:
| Platform | Video shape | In practice |
|---|---|---|
| Instagram Reels | 1.91:1 to 9:16 | Make it 9:16 |
| Facebook Reels | 9:16, 1080 × 1920 | Make it 9:16 |
| TikTok | 9:16, vertical | Make it 9:16 |
| YouTube | 16:9, 1920 × 1080 (1080p) up to 7680 × 4320 (8K) | 16:9 for videos, 9:16 for Shorts |
| 1:2.4 to 2.4:1 | Vertical, square or wide all work | |
| X | 1:3 to 3:1 | Vertical, square or wide all work |
| 9:16, 1:2, 2:3, 3:4, 4:5 or 1:1 | 9:16 or 2:3 | |
| Threads | 9:16 recommended, up to 1,920 pixels wide | Make it 9:16 |
Cropping, bars and safe zones
When a video’s shape does not match the space it is shown in, the platform either crops it or adds bars. A 16:9 clip in a 9:16 Reel loses most of the frame or sits in a thin strip; a 9:16 clip on YouTube’s player is framed with padding at the sides.
Full-screen formats also lay buttons, captions and the account name over the bottom and right of the picture. Keep faces and on-screen text away from those edges, so nothing important sits under the interface.
One video, several shapes
Posting the same video everywhere usually means more than one shape:
- Shoot with room around the subject, so a 9:16 and a 16:9 crop both keep it in frame.
- Make the vertical version first if short video is where most of your views come from.
- Reframe each copy rather than squeezing it: a shape change should move the frame, not stretch the picture.
- Check the cover in each shape too, since a 9:16 cover is shown cropped to a square or 4:5 on some profile grids.
Aspect ratios in PostEase
Studio, the video editor in PostEase, makes vertical 9:16 for Reels, TikTok and Shorts, square 1:1, 4:5 and 3:4 for feeds and Pinterest, and 4:3 and 16:9 for YouTube and the web. Reframe keeps the subject in every clip, and a copy in another shape is one click.
Questions
What aspect ratio is 1080 × 1920?
9:16, the vertical full-screen shape used by Reels, TikTok and Shorts.
What is the best aspect ratio for Instagram?
9:16 for Reels, and 4:5 for feed photos, the tallest shape the feed shows without cropping.
Is 16:9 the same as 1920 × 1080?
1920 × 1080 is one 16:9 size. 3840 × 2160 is another; the ratio is the shape, the pixels are the size.
What happens if my video is the wrong shape?
The platform crops it or adds bars around it. Reframe it to the shape the platform shows instead.
Sources
- Instagram, Reel size and aspect ratios on Instagram, checked October 2026.
- YouTube, Video resolution and aspect ratios, checked October 2026.
- TikTok, Content Posting API: media transfer guide, checked October 2026.