Image Resizer
Use this free online Image Resizer to change a photo's dimensions by exact pixel size or by percentage, with an optional aspect-ratio lock so the picture never stretches. It is useful for sizing images for an email signature, hitting profile-picture requirements on a social network, preparing print artwork at a specific resolution, or shrinking high-megapixel phone photos before posting them online. Drop the image, type the new width or height, and download the resized copy. JPG, PNG and WebP are all supported. Resizing happens on an in-browser HTML5 Canvas, so the original photo is never uploaded to a server.
Click to choose or drag & drop an image
How to Use This Image Resizer
Resizing a photo takes one drag and two numbers.
- Drop your photo into the upload zone or click to choose a file.
- Pick the resize mode — exact pixels or a percentage of the original.
- Type the new width; the height auto-fills if 'lock aspect ratio' is on.
- Click Resize Image to render the new version.
- Click Download to save the resized image; the original is untouched.
How This Image Resizer Works
Resizing changes the number of pixels in an image. Reducing the pixel count is called downsampling — the algorithm averages neighbouring pixels into single new ones, which is why a downscaled photo looks smooth. Increasing the pixel count is called upsampling — the algorithm has to invent pixels, typically through bilinear or bicubic interpolation, which is why upscaling rarely makes a photo look sharper, only larger. The resizer uses the browser's built-in Canvas drawing API, which performs bilinear interpolation by default — a good default for both upscaling and downscaling. Locking the aspect ratio multiplies the original width-to-height ratio by your chosen percentage so the photo never stretches; unlocking it lets you stretch the image deliberately if a layout requires it. The output is re-encoded into the same format as the input by default, but you can switch formats during the resize by saving the result through the Image Compressor. Because everything runs locally in JavaScript there is no upload limit and no server-side privacy concern — the photo never leaves your device.
Last updated: May 2026.
Frequently Asked Questions
Will resizing reduce my image's quality?
Reducing size loses some detail by definition, but if the new size is at least the size you display, it's indistinguishable. Enlarging a small image always reduces visible quality.
What are the popular preset sizes for?
1920×1080 = Full HD video frames or hero banners. 1080×1080 = Instagram square. 1200×630 = Facebook/LinkedIn Open Graph. 800×800 = generic square thumbnails.
Does the tool keep my original aspect ratio?
When the lock toggle is "Yes", changing one dimension auto-updates the other. Toggle to "No" if you want to force exact dimensions.
What output format does the resizer produce?
PNG if your input was PNG, JPEG otherwise. Quality is set to 92% for JPEG.
Can I resize transparent PNGs without losing transparency?
Yes — the tool keeps the alpha channel when converting between PNG sizes. Transparency is preserved.