How to Compress Images Without Losing Quality
Updated June 2026 · 4 min read
Large image files slow down websites, bounce off email size limits, and eat storage. Compressing them fixes all of that - but most "image compressor" sites upload your photos to a server first, which is slow and a poor idea for anything personal. Here is how to compress JPG and PNG images and shrink their file size with no visible quality loss, for free, entirely in your browser.
Can you really compress without losing quality?
Mostly, yes - and the reason is how our eyes work. JPG compression is "lossy", meaning it discards data, but it is very good at discarding detail you cannot see. At a high quality setting (around 80 percent), a photo can drop to a fraction of its original size while looking identical on screen. If you need a mathematically perfect copy, PNG uses "lossless" compression instead, which keeps every pixel but saves less space.
🔒 Open the image compressor
Compress JPG, PNG and WebP in bulk. 100% in your browser, nothing uploaded.
How to compress an image
- Open the image compressor.
- Drag in one or more images. They are processed on your device, never uploaded.
- Adjust the quality slider. Start around 80 percent and watch the resulting file size.
- Download the smaller image. A batch comes back as a ZIP.
The settings that actually matter
- Quality, not resolution, first. Lowering quality to 75 to 85 percent usually halves the file size with no visible difference. Try that before shrinking dimensions.
- Resize if it is bigger than it needs to be. A 6000-pixel photo displayed at 1200 pixels is wasting space. Use the image resizer to bring the dimensions down, then compress.
- Pick the right format. JPG for photos, PNG for screenshots and graphics with text. If a PNG photo is huge, converting it to JPG often saves the most.
Limitations to know
Compression is a trade-off: push the quality too low and you will start to see blocky artifacts, especially in skies and smooth gradients. Already-compressed JPGs have less room to shrink than a fresh export. And compressing a PNG will never make it smaller than the same image saved as a well-tuned JPG. When in doubt, compress, preview, and adjust.
FAQ
Can I compress an image without losing quality?
- You can reduce file size dramatically with no visible quality loss. JPG compression is lossy, but at a high quality setting (around 80 percent) the change is invisible while the file is much smaller. For a truly identical image, PNG offers lossless compression.
What is the best file size for a web image?
- For most web and email use, aim for under 200 KB per image, and under 1 MB for a large hero photo. A compressor lets you trade quality for size until you hit your target.
Does compressing happen on a server?
- Not with OpenConvert. The image is compressed in your browser, so it is never uploaded. That keeps it private and avoids the upload and download wait.
Can I compress many images at once?
- Yes. Drop in a batch and they are compressed together on your device. A single image downloads directly; several come back as a ZIP.