Image Compressor
Shrink an image's file size with a quality slider, and see exactly how many bytes you saved before you download.
Drop an image here or click to upload
Supports JPG, PNG, WebP
How to use this tool
- Drop an image onto the upload area, or click it to choose a file.
- Move the quality slider. Lower numbers make a smaller file; higher numbers keep more detail.
- Click Compress Image, then compare the before and after previews that appear side by side.
- Check the file sizes in the two headings and the percentage saved next to the compressed one.
- If the result looks soft, slide the quality back up and compress again. Nothing is overwritten until you download.
About this tool
Reduce the file size of a photo by re-encoding it as a JPEG at a quality level you choose, with the original and the result shown side by side so you can judge the trade-off rather than guess at it. Compression matters wherever there is a size limit: email attachments that bounce, application portals that cap uploads at two megabytes, web pages that load slowly because someone dropped in a 6 MB hero image, and message threads that refuse to send. A phone photo is usually three to five megabytes and almost never needs to be. Quality is the only control, and that is deliberate. JPEG quality is a scale from heavily compressed to nearly lossless, and where the useful setting sits depends entirely on the picture. Photographs with a lot of texture hide compression well and survive 60 per cent. Flat colour, screenshots and text show artefacts early and want 85 or higher. The side by side preview is there so you can find the point where the file is small enough and the picture still looks right. Two things worth knowing. Compression here is lossy and one way: the discarded detail is gone, so always keep your original. And the output is always a JPEG, which means a transparent PNG will come back with a solid background. If you need to keep transparency, resize the PNG instead of compressing it. The whole thing runs on a canvas in your browser. Your photo is never uploaded.
Frequently asked questions
How do I reduce an image file size without ruining the quality?
Start at 80 per cent quality and compress. Compare the two previews at full size. If you cannot tell them apart, try 70 and look again; if you can see mush around edges or blotches in flat areas, go back up. Most photographs sit comfortably between 70 and 85 per cent, which typically removes 60 to 80 per cent of the file size with no visible change.
What quality setting should I use?
It depends on the image, not on a universal number. Detailed photographs hide compression well and often look fine at 60 to 70 per cent. Screenshots, logos, diagrams and anything with text or large flat areas show artefacts much sooner and want 85 or above. When in doubt, use the side by side preview rather than a rule of thumb.
Why is my compressed image sometimes larger than the original?
Because the original was already compressed harder than the setting you chose, or because it was a PNG that stored an image JPEG happens to encode inefficiently. Re-encoding an already small JPEG at 95 per cent can genuinely make it bigger. If that happens, lower the quality slider or keep the original.
Does compressing an image change its dimensions?
No. The pixel width and height stay exactly the same; only the amount of data used to describe each pixel changes. If you want fewer pixels as well, run the file through the Image Resizer first and then compress, which usually gives a far smaller file than either step alone.
What happens to a transparent PNG?
The output is a JPEG, and JPEG has no alpha channel, so transparent areas come back filled rather than see-through. If transparency matters, do not compress the file here. Resize it instead, or keep it as a PNG.
Is the compression lossless?
No. JPEG compression is lossy: it permanently discards detail your eye is least likely to miss, which is exactly why it can make files so much smaller. The discarded data cannot be recovered by compressing again at a higher quality, so keep your original file.
Are my images uploaded anywhere?
No. The file is read into your browser and re-encoded on your own device using a canvas. Nothing is sent to a server, stored or logged, so it is safe for personal photos and confidential material.