3840 x 2160 Resizer
3840 x 2160 pixels is 4K UHD: exactly twice Full HD on each side, four times the pixels overall. It's the target for 4K wallpapers and TV displays, and it's the size YouTube's help documentation now recommends for custom video thumbnails.
3840
width (px)
2160
height (px)
16:9
aspect ratio
Need other dimensions? Browse all Pixels sizes or use the free image resizer for any platform.
Sources
We check platform-specific dimensions against source documentation when available.
- YouTube Help - Add custom thumbnails on YouTube - YouTube's help page recommends 3840 x 2160 (4K) thumbnails (minimum width 640px, 16:9 ratio); 1280 x 720 remains a widely used, still-accepted baseline.
4K UHD: Four Times the Pixels of Full HD
At 3840 x 2160, an image carries just over 8 million pixels — double 1920 x 1080 on each side. On a 4K display it fills the screen natively, with no upscaling.Because it is an exact multiple of both 1080p and 720p, the same export downscales to those sizes perfectly cleanly.
YouTube's Recommended Thumbnail Size
YouTube's help documentation now recommends 3840 x 2160 for custom thumbnails — up from the long-standing 1280 x 720 baseline — so thumbnails stay sharp on TVs and high-density screens.The 16:9 ratio is unchanged, so an existing thumbnail composition scales straight up; just export from the highest-resolution source available rather than enlarging a small file.
A Future-Proof Master Copy
Keeping a 3840 x 2160 master means every downstream size — 1440p wallpaper, 1080p frame, 720p preview — is a clean downscale from the same file.The trade-off is file weight: for web pages that only display small previews, export a smaller derivative instead of shipping the full 4K image.
How to resize an image to 3840 x 2160?
- 1
Step 1: Choose your image
Pick the image from your library that you want to resize to 3840 x 2160 pixels.
- 2
Step 2: Upload and resize your image
Upload your image and use a tool to resize it to 3840 x 2160 pixels.
- 3
Step 3: Save the resized image
Once it's ready, save your resized image to your device.
It's 4K UHD, the consumer standard used by TVs, monitors, and streaming. Cinema “DCI 4K” is slightly wider at 4096 x 2160; for wallpapers, thumbnails, and video frames, 3840 x 2160 is the size that matters.
All Pixels Image Sizes
Choose the recommended Pixels dimensions for your content
File tools
Convert the resized image
Need a different file format or transparent background? Choose a focused converter, then check the preview and encoded size before downloading.
Put Your 3840 x 2160 Image Into a PDF
Put one image on each page, arrange the order, and create the PDF in your browser.
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