OnlineFreeToolBoxImage Tools
Image Compressor
Compress an image and compare Original vs Compressed, with sizes and reduction shown.
or drop an image here
Upload an image first. Nothing processed is shown before upload. Moving Quality re-processes live. After processing, download the compressed version at your chosen quality.
How compression works here
Your image is drawn onto an in-browser canvas and re-encoded as a JPEG at the quality level you choose, which reduces file size by simplifying color and detail data. Lower quality settings produce smaller files but can introduce visible artifacts, so it's worth comparing the preview before downloading.
When to compress images
Smaller image files load faster on websites, take up less space in emails and messages, and upload more reliably on slow connections. This is especially useful before adding photos to a website, since large uncompressed images are one of the most common causes of slow page load times.
Frequently asked questions
Will compressing my image make it look noticeably worse?
At moderate quality settings (60–85%), most photos show little to no visible difference while file size drops significantly. Very low quality settings (under 30%) can introduce visible blocky artifacts, especially in areas with fine detail.
Can I compress PNG files, or only JPG?
You can upload PNG, JPG, or WebP files. The compressed output is saved as JPG, which is the format best suited to quality-based compression — this means transparency in PNG files will be replaced with a white background.
Is there a file size limit?
There's no hard limit set by the tool, but very large images (many megapixels) may take a moment longer to process since everything runs on your device rather than a server.
Does compressing an image reduce its pixel dimensions?
Generally no — compression here reduces file size through encoding quality, not pixel dimensions. The one exception is a very high-resolution photo (well beyond typical camera output) which may be scaled down slightly to stay within limits mobile browsers can safely process. If you specifically need to resize width and height, use the Image Resize & Crop tool instead, which includes quality control too.
Why does it say "Already optimal" instead of a percentage?
Some images — particularly PNG screenshots and photos that have already been compressed elsewhere — don't shrink further when re-encoded, and can occasionally come out larger. This tool checks for that and automatically keeps your original file whenever re-encoding wouldn't actually help, rather than handing back something bigger than what you uploaded.
Frequently asked questions
Does compression change the image size in pixels?
No. This tool keeps the pixel dimensions and reduces file size by re-encoding at the chosen quality.
Can I compress the same image twice?
Yes, but the second run usually saves very little, because the first compression already removed the easy savings. If you need a smaller file, lower the quality setting on the first run instead of compressing twice.
What quality should I choose?
70% is a good starting point for photos on the web. Lower quality gives a smaller file with more visible artefacts; higher quality keeps detail but saves less space.
Why is there nothing processed before I upload?
The tool only processes after you upload, so the comparison you see is always for your image, not a sample.
Does it work for PNG images too?
Yes, you can upload common image formats. The amount saved depends on the image: photos compress well, while simple graphics with flat colours may save less.