YouTube 4K video size: 3840 by 2160
3840 by 2160 is the 4K UHD upload frame. It is the same 16:9 shape as 1080p with double the width and double the height, giving four times the pixels at 8.29 megapixels.
At a glance
- Dimensions
- 3840 × 2160 pixels
- Simplified aspect ratio
- 16:9
- Decimal ratio
- 1.78:1
- Megapixels
- 8.29 MP (8,294,400 pixels)
- CSS aspect-ratio
- aspect-ratio: 16 / 9;
- Preset category
- Video
- Where it is used
- Ultra high definition uploads and 16:9 masters that will be downscaled
In detail
The relationship to 1080p is exact rather than approximate. Doubling both dimensions doubles the linear resolution and quadruples the pixel count, from 2.07 megapixels to 8.29, and it keeps the ratio identical at 16:9. That exactness is why a 4K master downscales to 1080p cleanly with no resampling artefacts at the edges.
Uploading above the resolution your audience watches at is not vanity. A larger source gives the platform's encoder more information to work with, so the 1080p rendition it produces from a 4K master generally holds up better in high motion scenes than one encoded from a native 1080p file. The cost is upload time and storage, both of which scale with the pixel count.
The same four times factor works against you everywhere else. Colour grading, effects and exports all take roughly four times as long, and a proxy workflow, editing against low resolution stand ins and relinking the originals at export, exists precisely because of that arithmetic.
The image resizer has a 4K UHD 3840 by 2160 preset, so a still frame or a title card can be produced at exactly this size without typing dimensions. It caps at 8192 pixels on a side, which leaves plenty of headroom above this frame.
Examples
3840 / 1920 = 2
2160 / 1080 = 2
(3840 * 2160) / (1920 * 1080) = 4 // four times the pixels
3840 / 2160 = 1.7778 // the same 16:9 shape<img
src="/frame-4k.jpg"
width="3840"
height="2160"
style="width: 100%; height: auto"
alt="Opening frame">The intrinsic attributes let the browser reserve a 16:9 box before the file arrives.
Things that catch people out
- 4K UHD at 3840 wide is not the same as the cinema 4K standard at 4096 wide. The two are different shapes and mixing them in one timeline causes a crop.
- A 4K file that was upscaled from a 1080p source has four times the pixels and no more detail, so it costs bandwidth and buys nothing.
- Quadrupled pixel counts hit memory as well as time. Browser based processing of a 4K still needs several times the working memory of a 1080p one.
Try it: Aspect Ratio Calculator
Enter a width and a height, or a ratio and one dimension, and it solves the missing one, simplifies the ratio, counts the megapixels and gives you a copyable CSS value.
Aspect Ratio Calculator
LOCAL · Browser-OnlyCalculate and convert aspect ratios for images, videos, and screens
1920 x 1080px · 16:9 · 1.7778:1
Common Aspect Ratios Reference
| Ratio | Decimal | Common Use |
|---|---|---|
| 16:9 | 1.778 | Widescreen TV, YouTube, monitors |
| 4:3 | 1.333 | Classic TV, iPad, presentations |
| 1:1 | 1.000 | Instagram square, profile pictures |
| 21:9 | 2.333 | Ultrawide monitors, cinema |
| 9:16 | 0.563 | Phone vertical, TikTok, Reels |
| 3:2 | 1.500 | 35mm photography, MacBook |
| 2:3 | 0.667 | Portrait photography, posters |
| 5:4 | 1.250 | Large format photography, older monitors |
| 32:9 | 3.556 | Super ultrawide monitors |
| 2.39:1 | 2.390 | Anamorphic cinema, widescreen films |
Related Image and canvas sizes
All image and canvas sizes →YouTube 1080p video size: 1920 by 1080
Why 1920 by 1080 is the standard full HD upload frame, what the player overlays cover, and how the thumbnail is a separate asset at the same shape.
4K UHD screen size: 3840 by 2160
The 3840 by 2160 UHD resolution, why it is named for a width it does not have, how it differs from cinema 4K, and what it costs to process.
16:9 aspect ratio
Where the 16:9 ratio came from, the pixel dimensions that hit it exactly, what it suits, and the places where a widescreen frame is the wrong shape.
YouTube Shorts size: 1080 by 1920
The 9:16 Shorts frame at 1080 by 1920, how it compares to the Stories and TikTok frame it shares pixels with, and where the interface covers your picture.
Instagram post size: 1080 by 1080
The 1:1 square post at 1080 by 1080, why the square survived the move away from it, and how it compares to the taller portrait frame in the feed.
Instagram Story size: 1080 by 1920
The full screen 9:16 Story frame, the interface that sits over its top and bottom edges, and how it differs from the feed formats in the same account.
Tools for this
- Aspect Ratio Calculator Free online aspect ratio calculator - calculate and convert aspect ratios for images, videos, and screens
- Image Resizer Free online image resizer - resize images to exact dimensions, percentage, or common presets