Upscale image to 4K in your browser
OpenPixels (openpixels.app) is a free photo enhancer that runs on your own device. To upscale image to 4K, you pick a multiplier rather than a target size, and this page shows which one to pick. The photo is never uploaded.
Free, open source, no account, no watermark. Works offline once its model has downloaded.
Upscale image to 4K: which size to pick.
There is no “4K” setting. Under Size you choose 2×, 4× or 8×, and the result is the original size times that number. 4K UHD is 3840 × 2160 pixels, so look at how wide your photo is:
1920 px wide or more
Choose 2×. A 1920 × 1080 screenshot comes out at 3840 × 2160.
960 to 1919 px wide
Choose 4×. A 1280 × 720 frame comes out at 5120 × 2880, above 4K.
480 to 959 px wide
Choose 8×. Smaller than 480 px, even 8× falls short of 4K.
The result keeps your photo’s own shape. A square photo becomes a larger square, not a 16:9 frame, so it is 4K wide rather than exactly 3840 × 2160.
Upscale image to 4K in five steps.
- Open the app and press Choose a photo, or drop the photo anywhere on the page.
- Under Size, choose the multiplier from the table above.
- Under What is it, keep Photograph, or choose Drawing or anime for an illustration.
- Press Enhance, then drag the slider to compare Original with Result.
- Press Save the photo. The file name says the multiplier, such as
holiday-4x.png.
To upscale image to 4K for a whole folder, open Several at once: the same multiplier is applied to every photo, and Download all as a ZIP gives you the results in one file.
It checks that the detail is real.
After you upscale image to 4K, OpenPixels shrinks the result back to the size you started with and compares it with your photo. When the two still match, the panel under the result says Faithful to the original: the detail was enlarged rather than invented.
What 4K can and cannot mean here.
A 4K image is about 8.3 megapixels. The web app holds the result near 40, and the Android app near 16, so 4K fits in both. When a photo is already large, the app says how far it can go before anything runs.
Enlarging adds pixels. It cannot recover detail that was never captured: a clean small photo enlarges well, and an out-of-focus one stays soft, only larger. For a soft photo, try the image sharpener first.
For print, a 3840-pixel-wide image is about 12.8 inches wide at 300 dots per inch.
Upscale image to 4K now.
It also enlarges photos in the browser to any of the three sizes, handles drawings and anime, and comes as software for Windows, Mac and Android.
Open OpenPixels →Before you open it.
Can I upscale an image to 4K for free?
Yes. OpenPixels is free, with no account, no watermark and no limit on how many photos you process. The work is done in your browser, on your own device, and the photo is never uploaded.
Is there a 4K button?
No. You choose how much larger to make the photo: 2×, 4× or 8×. To upscale an image to 4K, pick the multiplier that takes its width to 3840 pixels or more: 2× from 1920 pixels wide, 4× from 960, 8× from 480.
Will the result be exactly 3840 × 2160?
Only if the photo is exactly 1920 × 1080, 960 × 540 or 480 × 270 before you start. The result keeps the photo’s own shape and is the original size times the multiplier, so it is usually a little larger than 4K.
Is 4K too large for the app?
No. A 4K image is about 8.3 megapixels. The web app and the Windows and Mac apps hold the result near 40 megapixels, and the Android app holds it to 16, so 4K is inside all of them.
Will a blurry photo look sharp at 4K?
Enlarging adds pixels; it cannot recover detail that was never captured. A small, clean photo enlarges well. A photo that is out of focus stays soft, only larger.
Can I upscale many images to 4K at once?
Yes. Several at once applies the same multiplier to any number of photos and gives you a ZIP of the results and a CSV of the measurements for each one.