Take a small photo up to a 4096px longest side — enough for 4K UHD (3840×2160) and DCI 4K (4096×2160) — free, unlimited, and processed in your own browser.
Runs entirely in your browser. Your image is never uploaded.
AI upscaling reconstructs detail that the pixels you already have imply. A clean 1024px photo, a game screenshot, or a crop from a poster will hold up at 4K. A blurry or heavily compressed source will not: the model enlarges the blur along with everything else, and JPEG blocking becomes four times more visible. If the source already looks soft at 100%, fix the source before you enlarge it.
A 4096px image covers a 4K monitor or TV outright, and at 300 DPI it prints about 34cm on the long edge — an A3 poster with room to trim. For video, remember that a 4K timeline wants 3840 or 4096 pixels of real width: upscale the still first, then bring it into the edit, rather than letting the editor stretch a small frame during export.
Yes. The model runs on your own device, so there is no server time to bill — 4× has no daily cap, no credits, and no account.
4096 pixels on the longest side, about 16.7 megapixels in total. Downloads are lossless PNG.
Pick 4× when you need 4K from a small source. Pick 2× when your source is already 1500-2048px: at 2× it keeps its full detail, while 4× would shrink it to 1024px first.
Yes, in a modern mobile browser. Phones without WebGPU fall back to the CPU path, which is slower, and a 4× job is the heaviest one there is — start with a small source.