Resize Images to Exact Pixel Dimensions or a Percentage

Set a target width and height, or scale by percentage, and watch the result update before you export.

About the Image Resizer

Two resize modes are available. Exact pixels lets you type a width and leave the height blank, in which case the height is calculated from the original aspect ratio; fill in both and untick keep aspect ratio if you deliberately want to distort. Percentage mode gives you a slider from 1 to 200 percent, starting at 50. A live preview redraws as you move any control, so you see the framing before committing.

Output format can stay matched to the input or be forced to PNG, JPG or WebP, with a quality slider from 10 to 100 for the lossy formats. Finished files are renamed to include their new dimensions, so a photo saved at 1200 pixels wide arrives as name-1200x800 rather than something you have to open to identify. Several images can be processed in one pass, which makes this a practical private image resizer for batches that should not be handed to a web uploader.

Key Features

  • Pixels or percentage: Type exact dimensions, or scale everything by a percentage between 1 and 200.
  • Automatic height: Leave the height field empty and it is derived from the width using the original proportions.
  • Deliberate distortion: Unticking keep aspect ratio lets you force a non-proportional size when a layout demands it.
  • Live preview: The preview redraws as you change any setting, so you are not exporting blind.
  • Descriptive filenames: Each output is named with the dimensions it was saved at, which keeps a batch of variants straight.

How to Use the Image Resizer

  1. Add one or more images — JPG, PNG, WebP, GIF, BMP and SVG are all accepted.
  2. Choose exact pixels or percentage mode.
  3. Enter a width, leaving height blank for proportional scaling, or drag the percentage slider.
  4. Pick an output format and quality if you want something other than the input format.
  5. Check the preview, then resize and download.

How It Works

Resizing uses the browser Canvas API rather than any library: the image is decoded, drawn into a canvas of the target size with image smoothing set to high quality, and encoded with canvas.toBlob. Because it is a straightforward resample, enlarging beyond the original resolution invents no new detail — a 200 percent scale simply interpolates, and text or fine lines will look soft. Choosing JPG as the output flattens any transparency onto white, so keep PNG or WebP if the image has an alpha channel you need.

When You Need It

A school office uploading pupil photographs into a management system that caps images at a fixed pixel width has to resize several hundred files that are all pictures of children. Safeguarding policy usually forbids putting those anywhere but school-controlled systems, which rules out the convenient online resizer entirely. The same constraint appears when a charity resizes photographs of service users for a newsletter, or a recruiter standardises headshots before adding them to an internal directory.

FAQ

Frequently Asked Questions

How do I resize without stretching the picture?
Enter only the width and leave the height box empty. The height is then calculated from the original ratio. Keeping the aspect ratio option ticked has the same protective effect.
Can I make an image bigger without it going blurry?
Not really. Scaling above 100 percent interpolates between existing pixels, so the result gets larger but no sharper. Start from the highest resolution original you have rather than enlarging a small copy.
Why is my resized PNG now a JPG with a white background?
The output format was set to JPG, which cannot store transparency, so transparent pixels were filled with white. Set the format to PNG or WebP to keep the alpha channel.
Can I resize a whole folder of images at once?
Yes. Add as many files as you need and they are processed in a single run using the same settings, each one named with its final dimensions.
Is anything uploaded while the images are being resized?
Nothing is. The decode, redraw and encode steps all run inside the browser using the canvas, so photographs of identifiable people never leave the computer they were opened on.
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