About the image resize tool
The image resize tool changes the pixel dimensions of a JPEG, PNG or WEBP image. It is intended for everyday tasks such as preparing an image for a specific slot on a website, meeting the size requirements of a form, or reducing the resolution of a photo before sharing it.
All processing happens in your browser using JavaScript. When you select an image, the tool reads it directly from your device, draws it at the new dimensions you specify, and downloads the result from the same browser session. Your image is not uploaded to any server.
The preview updates as you change the width, height, format or quality setting, so you can see the effect of each change before downloading.
How to resize an image
Using the tool takes only a few steps.
- Select an image from your device, or drag it into the upload area.
- Enter a new width, a new height, or both.
- Keep the aspect ratio if you want the image to avoid being stretched.
- Choose an output format and, if applicable, a quality level.
- Click the download button to save the resized image.
The tool shows a live preview of the resized image alongside the original, so you can compare the result before saving.
Understanding image resizing
Resizing changes the number of pixels in an image. When the new size is smaller than the original, the tool has to combine pixels, which is known as downscaling. When the new size is larger, the tool has to estimate new pixels, which is known as upscaling.
- Downscaling usually produces good results and reduces file size.
- Upscaling cannot add detail that was not in the original, so very large enlargements can look soft.
For the best results, work from the highest resolution original you have, and downscale to the size you need rather than upscaling a smaller image.
Keeping the aspect ratio
The aspect ratio is the relationship between the width and the height of an image. A photo with a 3 to 2 ratio, for example, has a width that is one and a half times the height.
When the aspect ratio is kept, changing one dimension automatically updates the other, so the image does not appear stretched or squashed. When the aspect ratio is not kept, both dimensions are applied exactly as entered, which can distort the image if the ratio is different from the original.
For photographs and most everyday images, keeping the aspect ratio is the safer choice. Turning it off is useful when the image must fit an exact box shape, for example a square thumbnail.
Choosing an output format
Each image format has strengths and weaknesses. Choosing the right format depends on how the image will be used.
- JPEG is well suited to photographs and other images with smooth transitions.
- PNG is well suited to screenshots, logos, diagrams and images with text.
- WEBP is a modern format that supports both lossy and lossless compression.
For PNG output, the quality slider has a smaller effect because PNG is lossless. For JPEG and WEBP, lowering the quality value reduces the file size at the cost of some detail.
Practical uses
- Preparing an image for a specific slot on a website or application.
- Meeting the size requirements of a form or upload page.
- Reducing the resolution of a photo before sharing it.
- Creating thumbnails or previews from larger images.
- Making an image fit an exact square or rectangular shape.
For repeated work on many files, a dedicated desktop tool is often faster than working through a browser. The tool here is best suited to occasional, one at a time tasks.
Limitations
- Upscaling cannot add detail that is not present in the original image.
- Entering both dimensions without keeping the aspect ratio can distort the image.
- Transparency is lost when converting to JPEG.
- Very large images may be slow to process on devices with limited memory.
- The tool processes one image at a time and does not offer batch resizing.
If the image contains sharp edges, text or fine patterns, it is worth checking the preview carefully before saving, since resizing can blur these features at very small sizes.
Frequently asked questions
Important information
This tool is provided for general informational and personal use. It performs resizing in your browser and does not provide legal, financial or professional advice.
Always keep an original copy of any important image before resizing it. Resizing rewrites the file, and in particular reducing the size discards detail that cannot be recovered.
For images that will be printed at large sizes, work from a high resolution original and avoid enlarging small images to a much larger size.