You need to email a batch of photos, upload product images to a website, or attach screenshots to a support ticket—but the files are too large. Compression can help, but the useful setting depends on the image and where it will be used.
How to compress images
- Open the Image Compressor
- Drop your images into the upload area (or click to browse). Accepts JPG, PNG, and WebP.
- Start with a high-quality setting, then lower it in small steps
- Preview the compressed result and compare file sizes
- Download your compressed images
Everything runs in your browser. Your images never leave your device.
If the image is much wider or taller than you need, use the Image Resizer first. Reducing pixel dimensions before compression avoids spending bytes on detail that will never be displayed.
How much will the file shrink?
There is no trustworthy fixed percentage. Results vary with dimensions, format, existing compression, transparency, and image detail. A file that is already optimized may change very little; an oversized camera photo may have much more room to shrink.
Use the before-and-after size shown by the compressor, then inspect the output at the size people will actually view it. Pay particular attention to gradients, small text, faces, and sharp edges.
- Photos can tolerate some lossy compression, but fine texture may disappear first.
- Screenshots and text expose ringing or blur around sharp edges.
- Transparent graphics need an output format that preserves transparency.
JPG vs PNG: which to compress?
JPG is already a lossy format — it was designed for photos and handles compression well. Reducing quality from 100 to 80 removes data that's invisible to most people.
PNG is lossless by design. The compressor reduces PNG file size by optimizing the encoding without discarding data. You can be more aggressive with PNG compression without worrying about visual artifacts.
WebP supports both lossy and lossless compression. If your destination accepts it, compare a WebP output with JPG or PNG rather than assuming one format will always be smaller.
When does quality loss become visible?
Lower JPG quality settings can introduce block patterns in gradients, smearing around sharp edges, and halos around text. The point where those artifacts become objectionable varies by image, so compare the preview instead of relying on one universal threshold.
For PNG, quality loss isn't a factor — the compression is lossless. File size reduction comes from smarter encoding, not discarding pixels.
Does compressing an image reduce its resolution?
No. Compression reduces file size by optimizing how pixel data is stored. The dimensions (width x height) stay the same. Resolution and file size are different things.
Can I compress multiple images at once?
Yes. Drop a batch of images into the compressor and they'll all be processed. Download them individually or as a batch.
Is 80% quality good enough for a website?
There is no single ideal percentage or file-size target for every website. Start high, lower the setting gradually, and stop when the image still looks right at its rendered dimensions and meets the destination's actual upload or performance requirement.
Should I compress images before converting to PDF?
It can help. If you're assembling images into a PDF using the PNG to PDF converter or JPG to PDF converter, test compressed copies first and compare the finished PDF with the destination's size requirement.
For the full resize, format, and compression sequence, see how to reduce an image file size.