About the image compression tool
The image compression tool reduces the file size of a JPEG, PNG or WEBP image. It is intended for everyday tasks such as shrinking a photograph before sending it by email, reducing the size of images before uploading them to a website, or saving space in a photo collection.
All processing happens in your browser using JavaScript. When you select an image, the tool reads it directly from your device, re encodes it at the quality and format you choose, and downloads the result from the same browser session. Your image is not uploaded to any server.
This approach has practical advantages. There is no waiting time for uploads, no server side copies of your images, and the tool works even on a slow connection once the page has loaded.
How to compress an image
Using the tool takes only a few steps.
- Select an image from your device, or drag it into the upload area.
- Choose a quality level using the slider.
- Choose an output format: JPEG, PNG or WEBP.
- Click the compress button to process the image.
- Download the compressed file when the download begins.
The tool shows a preview of the original and compressed images side by side, so you can compare them before deciding whether to keep the result.
Understanding image compression
Image compression reduces file size by storing the image with less data. There are two broad categories.
- Lossless compression stores the image exactly, using an efficient internal structure.
- Lossy compression discards some detail, which is usually invisible at normal viewing sizes.
JPEG is a lossy format, which is why the compression tool can produce much smaller files than the original in most cases. The trade off is that a very low quality setting can introduce visible artefacts around sharp edges and in areas of fine detail.
For a photograph that will be viewed on a screen, a JPEG quality of around 70 to 80 percent usually provides a good balance between file size and visual quality. For images that will be printed, a higher quality setting is preferable.
Choosing a quality level
The quality slider controls how much detail is preserved. A higher value keeps more detail but produces a larger file. A lower value produces a smaller file with less detail.
- A value around 80 to 90 percent is suitable for photographs that will be printed.
- A value around 60 to 80 percent works well for photographs viewed on screen.
- A value around 40 to 60 percent is useful for thumbnails and quick previews.
- A value below 40 percent is only appropriate when file size is the main concern.
It is worth testing one or two settings on a single image before processing a whole collection. The result often varies depending on the type of image and the amount of fine detail it contains.
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.
When the output format is PNG, the quality slider has a smaller effect because PNG is a lossless format. The main size savings come from the JPEG or WEBP options, which apply lossy compression.
Practical uses
- Reducing the size of a photograph before sending it by email.
- Preparing images for a website while keeping page load times reasonable.
- Reducing the size of a photo library before uploading or archiving it.
- Shrinking screenshots before sharing them in a document or message.
- Meeting file size limits on forms and upload pages.
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
- Compression discards some detail and is not reversible.
- Very low quality settings can produce visible artefacts.
- 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 compression.
If an image contains sharp edges, text or fine patterns, it is worth checking the result carefully, because lossy compression can blur these features at low quality settings.
Frequently asked questions
Important information
This tool is provided for general informational and personal use. It performs compression in your browser and does not provide legal, financial or professional advice.
Always keep an original copy of any important image before compressing it. Compression rewrites the file, and while the visual result is usually very close to the original, some detail may be lost in a way that cannot be reversed.
For images that will be printed at large sizes, or used in professional publishing, work from a high quality original and apply compression only to the final output copy.