Ijharul Islam
1080×1920 is a 9:16 aspect ratio: vertical full HD, the shape of TikTok, Reels and YouTube Shorts. Turned on its side, 1920×1080 is 16:9. 1080×1350 is 4:5, 1080×1080 is 1:1 and 1440×1080 is 4:3. You get the ratio by dividing the width and height by their greatest common divisor: 1080 and 1920 share 120, which leaves 9 and 16.
More on this topic: Video formats, codecs and numbers, every guide in one place.
Below is a chart of 20 common resolutions with their exact ratios, how to calculate any ratio or missing side, and the few odd sizes that don't reduce to a tidy pair.
The short answer
Common answers: 1920×1080, 1280×720, 2560×1440 and 3840×2160 are 16:9; 1080×1920 and 720×1280 are 9:16; 1080×1080 is 1:1; 1080×1350 is 4:5; 1080×1440 is 3:4; 1440×1080 and 640×480 are 4:3; 2560×1080 is 64:27 (sold as 21:9). To find a missing side, multiply or divide by the ratio: a 9:16 video 1080 wide is 1080 × 16 ÷ 9 = 1920 tall.
Key takeaways
- Aspect ratio = width ÷ height, written in lowest terms.
- 9:16 and 16:9 are the same shape, vertical and horizontal.
- Some screens are only close to a standard ratio: 1366×768 is 683:384, which rounds to 16:9.
- 21:9 is a marketing name; 2560×1080 is really 64:27 (2.37:1).
- Keep both sides even numbers, because most H.264 and H.265 encoders need them.
What aspect ratio is 1080×1920?
1080×1920 is 9:16. The greatest common divisor of 1080 and 1920 is 120; 1080 ÷ 120 = 9 and 1920 ÷ 120 = 16. As a decimal it's 0.5625 (width divided by height). It's the standard full-screen vertical size for short-form video; Instagram's help page, for example, lists 1080 by 1920 pixels for Reels. Instagram's, TikTok's and YouTube's own size guides are collected in our social media video size guide.
Video aspect ratio chart: common resolutions
Each ratio below is the exact reduced fraction; the decimal is width ÷ height.
| Resolution (W × H) | Aspect ratio | Decimal | Commonly called |
|---|---|---|---|
| 3840 × 2160 | 16:9 | 1.778 | 4K UHD |
| 2560 × 1440 | 16:9 | 1.778 | 1440p, QHD |
| 1920 × 1080 | 16:9 | 1.778 | 1080p, Full HD |
| 1280 × 720 | 16:9 | 1.778 | 720p, HD |
| 854 × 480 | 427:240 | 1.779 | 480p widescreen (≈16:9) |
| 1366 × 768 | 683:384 | 1.779 | Laptop screens (≈16:9) |
| 1080 × 1920 | 9:16 | 0.5625 | Vertical Full HD (Reels, TikTok, Shorts) |
| 720 × 1280 | 9:16 | 0.5625 | Vertical HD |
| 2160 × 3840 | 9:16 | 0.5625 | Vertical 4K |
| 1080 × 1080 | 1:1 | 1.0 | Square |
| 1080 × 1350 | 4:5 | 0.8 | Portrait feed post |
| 1080 × 1440 | 3:4 | 0.75 | Portrait 3:4 |
| 1440 × 1080 | 4:3 | 1.333 | Classic TV, many phone photos |
| 640 × 480 | 4:3 | 1.333 | VGA, SD |
| 4096 × 2160 | 256:135 | 1.896 | DCI 4K (≈1.9:1) |
| 2560 × 1080 | 64:27 | 2.370 | Ultrawide, sold as 21:9 |
| 3440 × 1440 | 43:18 | 2.389 | Ultrawide QHD (≈2.39:1) |
| 1920 × 804 | 160:67 | 2.388 | Cinemascope crop of 1080p (≈2.39:1) |
| 1200 × 628 | 300:157 | 1.911 | Link preview images (≈1.91:1) |
| 1600 × 900 | 16:9 | 1.778 | HD+ (900p) |
If a size isn't here, type it into the free video aspect ratio calculator: it reduces any width and height to a ratio, shows the nearest standard shape and how far off it is, and works out a missing side rounded to an even number. It's free, runs in your browser and never uploads anything. Pinterest's accepted shapes and sizes are in Pinterest video size.
Which aspect ratio should you use on each platform?
Use 9:16 for full-screen short video and 16:9 for regular YouTube and most website video. The usual picks:
| Where | Ratio | Common size | Details |
|---|---|---|---|
| YouTube videos | 16:9 | 1920 × 1080 (or 3840 × 2160) | YouTube export settings |
| YouTube Shorts | 9:16 | 1080 × 1920 | Shorts size and length |
| Instagram Reels | 9:16 | 1080 × 1920 | Reels dimensions |
| TikTok | 9:16 | 1080 × 1920 | TikTok video size |
| Feed posts that take more screen | 4:5 | 1080 × 1350 | Portrait, fills more of a phone feed than square |
| Square posts | 1:1 | 1080 × 1080 | Shows the same in most feeds |
| LinkedIn video | Several | See the guide | LinkedIn video specs |
| YouTube thumbnails | 16:9 | 1280 × 720 | YouTube thumbnail size |
Platforms change their accepted ranges from time to time; each guide above links the platform's own help page. A 9:16 video also plays inside a 16:9 player with bars at the sides, which is why one vertical master often covers several platforms.
How do you calculate an aspect ratio?
Divide the width and the height by their greatest common divisor (GCD), the largest number that divides both exactly:
- Find the GCD. For 1080 and 1350 it's 270.
- Divide both sides by it: 1080 ÷ 270 = 4 and 1350 ÷ 270 = 5.
- Write width first: 4:5.
If the result is a pair of large numbers like 683:384, the size isn't an exact standard ratio. Compare the decimal with the standard ones (1.778 for 16:9, 1.333 for 4:3, 0.8 for 4:5) to find the nearest shape.
How do you find the height or width for an aspect ratio?
Multiply the side you know by the ratio, then round to an even number. For a ratio of W:H:
- Height = width × H ÷ W. For 16:9 at 1280 wide: 1280 × 9 ÷ 16 = 720.
- Width = height × W ÷ H. For 4:5 at 1350 tall: 1350 × 4 ÷ 5 = 1080.
| Ratio | Width 720 | Width 1080 | Width 1920 | Width 3840 |
|---|---|---|---|---|
| 16:9 | 720 × 406* | 1080 × 608* | 1920 × 1080 | 3840 × 2160 |
| 9:16 | 720 × 1280 | 1080 × 1920 | 1920 × 3414* | 3840 × 6826* |
| 1:1 | 720 × 720 | 1080 × 1080 | 1920 × 1920 | 3840 × 3840 |
| 4:5 | 720 × 900 | 1080 × 1350 | 1920 × 2400 | 3840 × 4800 |
| 4:3 | 720 × 540 | 1080 × 810 | 1920 × 1440 | 3840 × 2880 |
* Rounded to the nearest even number; the exact values are 405, 607.5, 3413.3 and 6826.7. Even sizes matter because most H.264 and H.265 encoders store color at half resolution (4:2:0), which needs even widths and heights; odd sizes get rejected or padded.
What is the difference between aspect ratio and resolution?
Aspect ratio is the shape of the frame; resolution is how many pixels fill it. 1280×720, 1920×1080 and 3840×2160 are three resolutions with the same 16:9 shape, and each has 2.25 or 4 times the pixels of the one before. Changing resolution while keeping the ratio (scaling) never crops or distorts anything; changing the ratio always means cropping, padding or stretching.
| Resolution | Ratio | Pixels | vs 1080p |
|---|---|---|---|
| 1280 × 720 | 16:9 | 921,600 | 0.44× |
| 1920 × 1080 | 16:9 | 2,073,600 | 1× |
| 2560 × 1440 | 16:9 | 3,686,400 | 1.78× |
| 3840 × 2160 | 16:9 | 8,294,400 | 4× |
| 1080 × 1920 | 9:16 | 2,073,600 | 1× (same pixels, turned) |
How do you change a video's aspect ratio?
You change a video's aspect ratio by cropping, by padding, or by both. Stretching it to fit distorts people and text, so avoid it.
| Method | What happens | Free tool |
|---|---|---|
| Crop | Cuts the sides (or top and bottom) to the new shape; you lose part of the frame | video cropper |
| Pad (letterbox or pillarbox) | Keeps the whole frame and adds bars or a blurred background | video resizer |
| Reframe | Crops to vertical and follows the subject or speaker | AI reframing in a clipping tool |
Step-by-step guides: how to resize a video without cropping it, how to crop a video to any ratio and how to convert horizontal video to vertical. If you're making a new video, set the shape before you start: QuickVeed's AI video generator generates clips in 16:9, 9:16, 1:1, 4:3, 3:4 or 21:9, where the model supports them.
Frequently asked questions
What aspect ratio is 1080×1920?
9:16, the vertical full HD size used for Reels, TikTok and YouTube Shorts.
What aspect ratio is 1080×1350?
4:5. Divide both by 270 and you get 4 and 5.
Is 1920×1080 16:9?
Yes. Both divide by 120, giving 16 and 9.
What aspect ratio is 1366×768?
683:384, about 1.779, so it's treated as 16:9 although it isn't exact.
Is 21:9 the same as 2560×1080?
Close: 2560×1080 is 64:27, or 2.37:1. 21:9 is a rounded marketing label (2.33:1).
What aspect ratio is 4K?
3840×2160 (UHD) is 16:9. Cinema DCI 4K, 4096×2160, is about 1.9:1.
What aspect ratio is 1440×1080?
4:3. Both divide by 360, giving 4 and 3.
How do I find the height for a 4:5 video?
Multiply the width by 5 and divide by 4: 1080 wide gives 1350 tall.
Try it with your own video
Generate video in the shape you need, from 16:9 to 9:16, from a prompt or an image. Describe the video or paste your script, pick a voice, and judge the first draft for yourself. QuickVeed plans start at $18/month, and new accounts get a 14-day trial with 250 credits, no card needed. Sign up or see pricing.
Sources
Competitor details in this post were checked against these public pages in October 2026. Products and prices change, so confirm with each vendor before you decide.
