Image Compression FAQ

Compression re-encodes the image so it needs fewer bytes. Lossy formats such as JPG and lossy WebP discard fine detail that is hard to see. Lossless formats such as PNG store every pixel exactly but look for more efficient ways to pack the data. This tool can also reduce the number of colours in a PNG, which is lossy.

Lossless compression keeps every pixel identical to the original, so savings are limited. Lossy compression permanently removes some information in exchange for much smaller files. Most photos on the web use lossy compression because the change is usually hard to notice.

For JPG and WebP output, it sets the encoder quality from 10% to 100%. Lower values produce smaller files with more visible artifacts. For PNG output, lower quality reduces the colour palette, from up to 256 colours down to 16. At 100% the PNG is saved losslessly.

Yes, occasionally. If the original was already saved at a low quality, re-encoding it at a higher quality, or in a less suitable format, can increase its size. The result screen shows the real sizes and warns you when this happens, so you can keep your original.

Your browser decodes the image and re-encodes it with its built-in JPEG encoder at the quality you choose. Transparent areas, if any, are filled with white because JPG does not support transparency. Learn more on the JPG compressor page.

Below 100% quality, your browser reduces the image to an indexed palette of up to 256 colours and encodes a compact PNG, keeping full and partial transparency. At 100% it is saved losslessly. Older browsers fall back to our server, where transparent images are kept lossless. See the PNG compressor for details.

Browsers that support WebP encoding, such as current versions of Chrome, Edge and Firefox, compress the image locally using lossy WebP with transparency preserved. If your browser cannot create WebP files, the image is compressed on our server instead. Try the WebP compressor.

For photographs, WebP is often smallest, followed closely by JPG. For screenshots, logos and flat graphics, a palette PNG or WebP is usually best. Because results depend on the image, the easiest approach is to try two formats and compare the sizes shown.

Yes. Under Output format choose JPG or WebP to convert any supported image. Choose “Same” to keep the original format, including PNG.

At moderate settings (around 70–85% for photos), most people cannot see a difference at normal viewing size. At low settings you may notice blockiness, blurring, colour banding or halos around edges. Use the before-and-after comparison to check before downloading.

The tool first tries your chosen quality. If the file is too large, it searches for the highest quality that fits the target. If even the lowest quality is too large, it reduces the image dimensions step by step until it fits or reaches a practical minimum.

Encoders cannot produce an exact byte count. The tool aims for the best result at or below the target, so the file is usually slightly smaller. That is why sizes are described as approximate.

The tool returns the smallest result it could produce and tells you that the target was not reached. You can then try a different output format, or crop the image before compressing.

Only when you set a target size that cannot be reached by lowering quality alone. If that happens, the result shows both the original and new dimensions. Without a target, dimensions are never changed.

In modern browsers, compression to JPG, WebP and PNG runs on your device, so the image is not uploaded. If your browser cannot encode WebP or PNG, the image is sent to our server, processed in memory and returned immediately. Images are never saved to our storage or database. See our privacy policy.

Yes. Because the image is re-encoded, embedded metadata such as EXIF camera information and GPS coordinates is not included in the compressed file.

No. There is no registration or login.

Each image can be up to 20 MB. Extremely large pixel dimensions may also be limited by your device memory, or by server limits when the server fallback is used.

Not at the moment. The tool compresses one image at a time. Select Compress Another Image to start the next one without reloading the page.

Yes. It works in current mobile browsers on Android and iOS. You can choose photos from your gallery or camera roll. Very high-resolution images may be slower on older devices.

After compression, select Download Compressed Image. The file is saved with “-compressed” added to the original name, for example photo-compressed.jpg, so your original is never overwritten.

On Android, downloads usually appear in the Downloads folder or your browser’s download list. On iPhone, Safari saves files to the Downloads folder in the Files app. From there you can share the file or save it to Photos.