Video aspect ratios explained: 16:9, 9:16, 1:1, 4:5 and 2.39:1

What is an aspect ratio?

The width of a picture against its height, written as two numbers with a colon. 1920 × 1080 is 16:9 because both numbers divide by 120: 16 × 120 is 1920 and 9 × 120 is 1080. The ratio is the shape; the pixel count is the size. 1280 × 720, 1920 × 1080 and 3840 × 2160 are all 16:9, at three sizes.

Cinema writes ratios as a single number against 1: 1.85:1, 2.39:1. In that form 16:9 is 1.78:1 and 4:3 is 1.33:1.

When a video's shape differs from the screen's, the player adds bars: above and below a wider picture (letterboxing), at the sides of a taller one (pillarboxing). Nothing is wrong with the video; it simply does not fill that screen.

What are the common video aspect ratios?

Are YouTube videos in 16:9 or 4:3?

16:9. YouTube's help centre says the standard aspect ratio for YouTube on a computer is 16:9, and lists 1920 × 1080 and 3840 × 2160 among the sizes to encode at. Other shapes still play, because the player resizes to fit the video, so a 4:3 video shows with bars at its sides rather than stretched. YouTube asks you not to add bars of your own, since they stop the player resizing properly.

Shape also decides what kind of video it is. Since 15 October 2024, YouTube classes any upload that is square or vertical and up to three minutes long as a Short. To keep a video in the main feed, make it wider, such as 16:9.

Horizontal vs vertical video: which should you use?

The one that matches how the screen is held. People turn a phone sideways to watch something properly and keep it upright to scroll:

• Horizontal, 16:9, for YouTube's main feed, television, a website or a presentation.
• Vertical, 9:16, for Shorts, Reels and TikTok. TikTok's video ad specifications recommend vertical 9:16, at least 540 × 960. Instagram's help centre accepts reels anywhere from 1.91:1 to 9:16, at a minimum of 720 pixels and 30 frames a second, but only 9:16 fills the screen.
• Square or 4:5 for feed posts, where a taller frame holds more of the screen as people scroll past.

So what is the best aspect ratio for a video? The shape of the screen most of your viewers will hold. If that is more than one screen, make more than one shape.

How do you convert 16:9 to 9:16?

Crop around the subject, never the middle. A 9:16 frame cut from a 16:9 picture of the same height keeps under a third of its width, so a centre crop often loses the person speaking or leaves an ear in shot. There are three ways to do it:

1. Crop and follow. Keep the crop on the subject and move it when they move. The standard for talking heads.
2. Stack panels. Put two pictures one above the other, such as host and guest, each cropped around a face.
3. Fit over a background. Shrink the wide picture into the middle of the tall frame over a blurred copy of itself. Everything stays, but the subject ends up small.

Shoot with the crop in mind when you can: 4K footage cropped to 1080 × 1920 keeps full detail. How to convert horizontal video to vertical goes step by step, and how to turn a long video into shorts covers choosing the moments.

How does Sharpy handle aspect ratios?

It asks. Sharpy never guesses the shape of the finished video: you decide it once, with File ▸ Decide the Finished Piece…, as a width and a height, a ratio with its long edge ("9:16 at 960 on the long edge"), or a destination such as vertical, square, portrait or widescreen. A reference video's shape is offered as a proposal to confirm, never taken as the answer, and until you decide, the viewer shows the recording's own shape and says so.

Then it holds every shape to what it means:

• One recording, every shape. The same recording gives 16:9, 9:16, 1:1 or 4:5, each reframed around its own subject rather than cut from the middle, with the frame following the speaker as they move.
• Words that stay readable. Text positions are kept as a share of the frame, so captions sit in the same place at every size. On vertical pieces, captions and the words in graphics are held clear of the TikTok and Reels buttons, and captions go below the chin or above the brow rather than across a face.
• Exact sizes. The vertical destination renders 1080 × 1920 and square renders 1080 × 1080. A 2.39:1 frame 1920 wide is 803.3 pixels tall, so Sharpy makes it 804 for H.264 and 803 for ProRes, and says so. The only sizes it refuses are ones the codec cannot write, and it names the nearest it can.
• Phone footage the right way up. A phone stores a portrait video on its side; Sharpy treats it as vertical everywhere.

How to export a video covers the rest of the finished piece: quality, loudness and files.

Sources

Checked on 18 October 2026.

• YouTube Help: video resolution and aspect ratios
• YouTube Help: three-minute YouTube Shorts
• TikTok Ads Manager: video ad specifications
• Instagram Help Center: reel size and aspect ratios