Image Compressor
Shrink an image's file size right in your browser. Nothing is uploaded to a server - your image never leaves your device.
Click to choose an image, or drag and drop it here
How image compression actually works
Digital images store an enormous amount of pixel data, and much of it is redundant or imperceptible to the human eye. Compression algorithms exploit this by simplifying color gradients, discarding data the eye is unlikely to notice, and packing the remaining information more efficiently. JPEG compression, in particular, works by dividing an image into small blocks and reducing detail within each block based on the quality level you choose — higher quality preserves more of the original detail, while lower quality sacrifices some fine detail in exchange for a dramatically smaller file.
This tool uses your browser's built-in Canvas API to perform that re-encoding directly on your device. Nothing is uploaded to a remote server for processing, which means your images never leave your device, there's no wait for an upload/download round trip, and there's no file size limit imposed by a server-side upload restriction.
Why file size matters
Large image files slow down websites, use more mobile data, and take longer to send over email or messaging apps that have attachment size limits. A photo straight off a modern phone camera can easily be 4-8 MB — compressing it to a fraction of that size, often with no visible quality loss, is one of the simplest ways to speed up a website or reduce storage use.
Choosing the right quality setting
There's no universal "correct" quality percentage — it depends on what the image is for. For web use where speed matters most, 60-75% quality is often indistinguishable from the original to a casual viewer while cutting file size significantly. For images you might print or zoom into, staying closer to 85-95% preserves more fine detail at the cost of a larger file.
Does this reduce image dimensions?
No, this only reduces file size through compression quality. Use the Image Resizer tool on this site if you also want to change the pixel dimensions of your image.
What quality setting should I use?
70-80% quality typically gives a large size reduction with little visible difference for most photos. Go lower only if file size matters more than visual quality, such as for thumbnail images or email attachments with strict size limits.
Why does PNG compress less than JPG?
PNG is a lossless format designed to preserve every pixel exactly, which is why it's often used for graphics, logos, and screenshots with sharp edges and text. JPEG is a lossy format built specifically for photographs, which is why it can achieve much smaller file sizes for photo content.
Is it safe to compress sensitive images this way?
Yes — since processing happens entirely in your browser using JavaScript, your image is never transmitted over the network or stored on any server, making it as private as editing a photo directly on your own device offline.
Works best with JPG and WebP images. PNG images are lossless by nature, so compression gains will be smaller.