Quick answer: To resize an image, choose a new width or height in pixels and let the other side follow the original proportions. Set both only when the target has the same aspect ratio as your image, or the picture will stretch. The free Image Resizer does this in your browser without uploading the file.
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Open the Image ResizerWhat resizing changes
A digital image is a grid of pixels. Resizing changes how many pixels the grid has, for example from 4000 × 3000 to 1600 × 1200. Fewer pixels usually means a smaller file and a faster web page.
Resizing is different from compressing. Compression keeps the dimensions and reduces the file size by encoding the pixels more efficiently. Resizing changes the dimensions themselves. The two are often combined: resize to the size the page actually displays, then compress.
The aspect ratio is width divided by height. A 4000 × 3000 photo has a 4:3 ratio. If the new size has a different ratio, the image must be either stretched or cropped to fit.
How to use the free Image Resizer
- Under Choose JPG, PNG or WebP image, select the file you want to resize.
- Enter the new Width, the new Height, or both, in pixels.
- Click Resize image.
- Check the preview and the result panel. It shows the new dimensions, the original size, the new size in KB and how much smaller the file is.
- Click Download image. The file is named
optimized-followed by the original name.
How the fields behave:
- Width only: the height is calculated to keep the original proportions.
- Height only: the width is calculated the same way.
- Both: the image is scaled to exactly that size. It is not cropped, so a different ratio stretches it.
The image is drawn on an HTML canvas in your browser and encoded with the canvas toBlob() method. The file is not uploaded.
Which format you get back
| Input | Output |
|---|---|
| JPG | JPG (saved with a .jpeg extension) |
| PNG | WebP |
| WebP | WebP |
The output is saved at 88% quality, which is lossy. PNG files become WebP because WebP keeps transparency and is usually much smaller. If you need a PNG file, for example for software that does not accept WebP, use a different tool.
Because the image is redrawn, the result does not keep the original EXIF metadata, such as camera details or GPS location.
Worked example: a camera photo for the web and a social card
For a blog post. A camera photo is 4000 × 3000 pixels and the article column is at most 1600 pixels wide. Enter 1600 in Width and leave Height empty. The height is calculated as 3000 × 1600 ÷ 4000 = 1200, so the result is 1600 × 1200 with the same 4:3 ratio.
For a 1200 × 630 social sharing image. Entering 1200 and 630 directly would squeeze the 4:3 photo into a 1.9:1 frame and make everything look wide. Instead, crop the photo first to the same ratio: 4000 × 2100 pixels (4000 × 630 ÷ 1200 = 2100). Then enter 1200 and 630. Because the ratios now match, nothing is distorted.
Common mistakes
- Filling both fields with a different ratio. The tool scales to exactly what you type, so faces and text stretch. Fill one field, or crop first.
- Upscaling small images. Making a 400-pixel image 1600 pixels wide adds pixels by interpolation, not detail. The result looks soft. Start from the largest original you have.
- Resizing the same file again and again. Each save is lossy. Keep the original and resize from it each time.
- Confusing pixels with print size. DPI settings only matter for printing. For screens and upload forms, the pixel dimensions are what count.
- Expecting a PNG back. A PNG input is saved as WebP, as described above.
Choosing the right size
- For web pages, match the largest width the image is actually displayed at, and use about twice that for sharp results on high-density screens if the file size allows.
- For upload forms, use the exact dimensions the form asks for, and crop first if the ratio is different.
- For email attachments, a long side of 1600 to 2000 pixels is usually enough to view on screen.
After resizing, compare the new file size with the original in the result panel. If the file is still too large for a form or page, compress it further with an image compressor rather than shrinking the dimensions below what the layout needs.
Frequently asked questions
Is my image uploaded when I resize it?+
No. The Image Resizer draws and encodes the image in your browser, so the file stays on your device.
How do I resize an image without changing its proportions?+
Enter only the width or only the height. The tool calculates the other side from the original aspect ratio.
Why did my PNG become a WebP file?+
The resizer saves PNG input as WebP because WebP supports transparency and is usually smaller. JPG input stays JPG and WebP input stays WebP.
Can I make a small image larger without losing quality?+
No tool can add real detail. Enlarging spreads the existing pixels over a bigger grid, so the result looks softer than the original.
Does resizing remove photo metadata?+
Yes. The image is redrawn on a canvas, so the downloaded file does not include the original EXIF data such as GPS location.