Image Resizer
Resize images to any dimension
100% free. Runs entirely in your browser - your files and data never leave your device and nothing is uploaded to any server.
4K UHD selected — upload an image to apply it.
Drag & drop files here
or browse to upload
Supports PNG, JPG, WebP up to 20MB
Processed in your browser - your file never leaves this device.
About this tool
The 4K UHD size is 3840 x 2160 pixels, a landscape 16:9 frame. Drop an image on this page and the preset is already applied - there is nothing to type in. This is the standard 4K UHD frame - four times 1080p, and what most modern TVs and monitors expect. Four times the pixels of 1080p, which is also four times the file size - worth checking before you attach one to an email. The image never leaves your computer - the resize runs in the browser, which also means there is no queue and no file-size cap. If your source is a different shape, the tool shows what will be cropped rather than silently squashing it. A 16:9 target always loses something from another ratio - seeing where is the difference between a usable result and a cut-off head.
How to use this tool
- Drop your image inAny JPG, PNG or WebP. Nothing is uploaded - your browser reads the file directly.
- It resizes to 3840 x 2160 pixelsThe 4K UHD preset is already selected on this page, so there is nothing to type in.
- Check the preview and downloadThe preview shows the exact crop. Reposition if you need to, then save as JPG, PNG or WebP.
Key features
- Resizes to exactly 3840 x 2160 pixels, the current 4K UHD size.
- Export as JPG, PNG or WebP, whichever the platform prefers.
- Live preview, so you see the crop before downloading instead of after.
- Runs in your browser - no upload, no account, no watermark.
- No limit on how many images you resize.
Common uses
- Resizing on a phone without installing an editing app.
- Preparing wallpapers or video stills at full 4K.
- Getting a correctly sized image without opening a full editor for a 30-second job.
- Preparing a batch at 3840 x 2160 pixels before a scheduled post.
- Fixing an image a platform rejected for being the wrong dimensions.
Tips for better results
- Four times the pixels of 1080p, which is also four times the file size - worth checking before you attach one to an email.
- Save as JPG rather than PNG at this size. A PNG photograph here can be several times larger for no visible gain.
- Check the result on the platform itself - feed thumbnails are often cropped again from the size you upload.
- Start from the largest original you have. Scaling up to 3840 x 2160 pixels from something smaller looks soft, and nothing undoes that.
Mistakes to avoid
- Letting the image stretch instead of keeping the ratio. A squashed face is more obvious than a tight crop.
- Re-saving the same JPG over and over. Each save loses a little more detail, permanently.
- Putting important detail near the edges of a 16:9 frame. Platforms crop again for thumbnails and previews.
- Assuming another platform at the same pixel size behaves identically. Four times the pixels of 1080p, which is also four times the file size - worth checking before you attach one to an email.
Frequently asked questions
3840 x 2160 pixels - a landscape 16:9 frame, 8.3 megapixels.
Drop it onto this page. The 4K UHD preset is already selected, so it resizes straight to 3840 x 2160 pixels and shows the crop before you download.
No. It keeps the 16:9 ratio and shows what will be cropped, so you can reposition before downloading rather than finding a bad crop afterwards.
No. The resize uses your own device image engine, so files never leave your computer.
Yes - free, no signup, no watermark and no limit on how many images you resize. It runs in your browser, so it costs nothing to provide.
JPG for photographs, PNG when there is text or transparency, WebP when the platform accepts it and you want the smallest file.
Yes. It runs in the browser, so it works on iPhone and Android as well as desktop, with no app to install.
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