Upscale image to 4K
AI that runs on your device: sharper and larger, and nothing is uploaded.
How to use it
Choose an image: a small photo, a screenshot or a scan.
Pick 1×, 2×, 3× or 4×, then press Upscale. It runs on your own device.
Compare the result with the original, then download it.
Which factor makes 4K
4K is 3,840 by 2,160 pixels. The page starts each photo on the smallest factor that brings its long side to 3,840 pixels:
| Your photo | Factor | Result |
|---|---|---|
| 960 by 540 | 4× | 3,840 by 2,160, exactly 4K |
| 1,280 by 720 | 3× | 3,840 by 2,160, exactly 4K |
| 1,920 by 1,080, Full HD | 2× | 3,840 by 2,160, exactly 4K |
| 640 by 480 | 4×, the most | 2,560 by 1,920 |
Why AI and not a plain resize
Stretching a photo to 4K makes it larger but softer: no new detail appears. The AI model, Real-ESRGAN, was trained to add the fine detail a larger photo would have, so edges, hair and text come out sharp.
Limits worth knowing
- Results go up to 16 megapixels, so 4K (8.3 megapixels) fits, from photos up to Full HD.
- A photo that is already 4K or larger is left at its size.
- Very small or very blurry photos improve, but can't become a true 4K photo: the AI can't recover what was never captured.
- It runs on your device: a phone can take a few minutes.
Frequently asked questions
How do I upscale an image to 4K?
Choose your photo: the factor that makes it 4K is already picked. Press Upscale, compare it with the original and download it.
What size is 4K?
3,840 by 2,160 pixels for a wide 16:9 picture. A photo of another shape becomes 3,840 pixels on its long side.
Can every photo become 4K?
Photos from 960 pixels across up to Full HD can. Smaller ones get the most the tool can do, 4 times larger, which is less than 4K.
Is the 4K upscaler free?
Yes: no sign-up, no watermark and no daily limit.
Is my photo uploaded?
No. The AI runs in your browser; the first time, it downloads the model and keeps it. Your photo is never sent anywhere.