How to Compress Images and Check the Quality
Reduce image file size in your browser, compare the result and understand quality settings. Compression savings and target file sizes are not guaranteed.
Image compression can make a photo easier to share, but there is no fixed percentage that every image can save. The result depends on the original encoding, dimensions, detail and chosen settings. An already optimized image may stay the same size or become larger.
Compress images step by step
- Open the Image Compressor.
- Select images or drag them into the file area. Batch processing is supported.
- Set Quality and Max size (MB). The defaults are 80 and 1 MB.
- Start conversion and compare the original and output sizes shown in the file list.
- Download the result and inspect details such as text, edges and gradients before sharing.
Processing takes place in your browser without sending the image files to a conversion server. Keep originals so you can try different settings without repeatedly compressing an already processed copy.
Quality and target size are different
For JPEG, WebP and AVIF, the tool starts with your chosen quality. If the output exceeds the target size, it tries lower quality settings. The final quality may therefore be lower than the slider value. The tool can still return a file larger than the target when those attempts are exhausted.
For PNG, it adjusts lossless compression effort rather than deliberately discarding pixel detail. BMP input is encoded as PNG. These paths also cannot guarantee the requested file size, and original metadata is not preserved by the pixel-based workflow.
The quality slider is not a promise that a particular percentage of the original information remains. Check the downloaded image at its intended display size and zoom in on details that matter.
If the output is still too large
- Use Image Resize to reduce dimensions if the image has more pixels than needed. Compression alone does not resize it.
- Try JPG to WebP or PNG to WebP when the destination accepts WebP. Compare the actual output rather than assuming a fixed saving.
- For a strict upload limit, check the downloaded file's size and leave some margin. A target setting does not guarantee acceptance by another service.
Common questions
Is this lossless? JPEG, WebP and AVIF use lossy encoding here. PNG compression preserves the decoded pixels, but does not promise a byte-identical original file or preserved metadata.
Can quality loss be invisible? Sometimes, at the intended display size. Fine text, textures and gradients can expose artifacts, so visual inspection matters.
Why does the tab slow down? Large images consume browser memory. Try smaller batches or dimensions, especially on mobile devices.