Resize an image to 4K (3840×2160)
Resize images to 3840×2160 (4K UHD) for wallpapers and displays, processed locally in your browser. High-quality scaling, nothing uploaded.
Privacy-first: every image is processed locally in your browser. Nothing is uploaded, stored or transmitted to any server.
4K needs honest expectations
3840×2160 is four times the pixels of Full HD — a target for wallpapers, digital signage and UHD displays. The catch: enlarging a smaller image cannot create detail that was never captured; upscaling interpolates, and past roughly 2× it shows. 4K output shines when the source is high-resolution to begin with, like modern phone and camera photos.
Best-quality scaling either direction
Downscaling a 40-megapixel shot to 4K uses stepped resampling for maximum crispness; modest upscales use smooth interpolation. Fill, Fit or Stretch map non-16:9 sources onto the frame, with the result previewed at full effect before you download. Even at these sizes everything runs locally — no upload of 20MB originals.
Frequently asked questions
- Does resizing happen on a server?
- No. Images are resized in your browser with high-quality step-down scaling for crisp results. Nothing is uploaded.
- Will resizing keep the aspect ratio?
- Yes by default. Enable “maintain aspect ratio” to fit within your target box without distortion, or turn it off to force an exact width and height.
- Are there presets for social media?
- Yes. There are presets for Instagram, Facebook, X/Twitter, YouTube and LinkedIn, plus common web, avatar and thumbnail sizes.
- Can I enlarge images?
- Yes, though enlarging cannot add detail that is not there. Downscaling produces the sharpest results.
- Can I resize images in bulk?
- Yes. Resize many images at once and download them together as a ZIP.