How to Compress Images for Websites and Uploads

Large images can slow uploads and consume more storage. Compression is useful when a website, application form or messaging service has a file-size limit, but the best setting depends on the purpose of the image.

What controls image file size?

Image dimensions, image detail, file format and compression settings all affect the final size. A high-resolution photograph contains much more information than a small graphic, so the same compression setting can produce different file sizes.

A practical compression workflow

1. Keep the original image as a backup.
2. Open the Image Compressor.
3. Select the image and choose an appropriate setting or target size.
4. Process the image and compare the result with the original.
5. Use the compressed copy only after checking that it still looks suitable.

Compression versus resizing

Compression reduces the amount of data used to represent an image. Resizing changes its dimensions. If an image is much larger than the space where it will be displayed, resizing it first can be sensible. The Image Resizer can be used when you need different dimensions.

Choosing a target size

If a form specifies a maximum size such as 50KB, 100KB, 150KB or 200KB, treat that number as a real upload requirement. Check the final file size rather than relying on a quality percentage alone. If no limit exists, avoid compressing more than necessary.

Quality checklist

• Read small text after compression.
• Check faces and fine details in photographs.
• Confirm the final extension is accepted by the destination.
• Keep the original for future use.

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