How to Compress PNG Image Online Free

PNG is the go-to format for images that need transparency, such as logos, icons, and screenshots. But PNG files can be enormous compared to JPEG — a screenshot from a 1080p screen can easily be 2–5MB as PNG. With the right compression technique, you can cut that to 400KB or less without any visible quality difference, while keeping full transparency support.

Why PNG Files Are So Large

PNG uses lossless compression, which means every single pixel's colour is stored precisely. This is great for quality but terrible for file size — especially for photos or images with gradients. There are two types of PNG reduction: lossless (removing metadata and optimising compression without changing a single pixel) and lossy quantisation (reducing the colour palette from millions to thousands, saving up to 70%).

How to Compress PNG Images

1. Open the Image Compressor at imgresizr.com.
2. Upload your PNG file.
3. If transparency is not required, click Convert to JPG for the maximum file size reduction.
4. If transparency must be preserved, adjust the quality slider — even PNG files benefit from quality reduction in this tool.
5. Download and verify transparency is intact before using in production.

When to Keep vs. Convert PNG

Keep PNG for Logos and Icons

If your image has a transparent background that will sit on coloured backgrounds, keep it as PNG. Converting to JPG will fill the transparency with white, destroying the effect. For logos on websites, SVG is even better than PNG — fully scalable with tiny file sizes.

Convert Screenshots to JPG

Screenshots that don't require transparency almost always compress much better as JPG than PNG. A 2MB PNG screenshot can often become a 200KB JPG with no perceptible quality difference when viewed on screen.