Drop an image below and this tool resizes it to 3840×2160 pixels, entirely inside your browser — no upload, no install, no sign-up. 3840×2160 is the standard 4K UHD resolution — 4x the pixel count of Full HD — used by 4K displays, TVs, and video exports.
With aspect ratio lock on (the default), the tool computes the matching dimension from your image's own proportions so the result isn't stretched or distorted — it never crops your photo. Turn the lock off if you need to hit this exact box regardless of your image's original shape.
Frequently asked questions
Yes, completely free, with no sign-up and no limit on how many images you resize.