How to compress an image
- Add your image Drop a file, choose one from your device, or paste from the clipboard.
- Set a target size Use the preset or enter your own limit in kilobytes.
- Download the result The tool returns the best quality that fits under the limit.
Why PNG compression is different
PNG is lossless: every pixel is preserved exactly. That is great for logos and UI screenshots, but it also means a photographic PNG can be much larger than the same image as JPG. Re-encoding a PNG through the browser usually saves only a small amount, and sometimes it can even grow.
SizeUnder is honest about that. It can reduce the dimensions or optimize the encoded file, but if you need a dramatic reduction on a photo, the better move is to convert to JPG or WebP. If you need transparency, WebP is often the best compromise.
What stays the same
- Transparent areas remain transparent in PNG output.
- Sharp edges and text are preserved better than with JPG.
- The image is never uploaded, so logos and unreleased designs stay private.
- Dimensions are reduced only when needed to reach the target.
PNG or WebP for the web?
Use PNG when a tool or workflow requires it, or when you need pixel-perfect lossless output. Use WebP for websites: it supports transparency, is much smaller for photographs, and is supported by all current browsers. For a logo that must work in older software, PNG is still the safest choice.
If a PNG cannot reach your target without becoming too small, try WebP output. It often cuts the file size by half while keeping transparency.
Frequently asked questions
Does compressing a PNG remove transparency?
No. When PNG is the output format, transparent pixels stay transparent. If you choose JPG output, transparency is flattened onto a white background.
Why is my PNG still large after compression?
PNG is lossless and inefficient for photos. The tool can resize it, but converting to WebP or JPG will usually produce a much smaller file.
Can I compress a transparent logo?
Yes. Keep PNG or WebP output to preserve the transparent background. JPG will fill transparent areas with white.
Does resizing a PNG make it blurry?
Downscaling removes pixels, so very small dimensions will look softer. The tool stops before the image becomes unusably small and tells you if the target cannot be met.
Last updated: November 12, 2026