Image Compressor
Cut an image's file size until it is small enough to send — and see exactly what you traded away.
Below about 60% you will start to see blocking around edges and text.
Reducing dimensions saves far more than quality alone. A 4000px photo rarely needs to be wider than 1600px on the web.
Original
Compressed
What the image Compressor does
This compressor re-encodes your image inside the browser. The file you choose is decoded by the browser's own image pipeline, drawn into a canvas at whatever size you pick, and re-encoded at the quality you set. The result is a new file built on your device — the original is never uploaded and never modified.
Two controls affect the size, and they are not equally powerful. The quality slider changes how aggressively the encoder discards detail; dropping from 100% to 75% typically removes more than half the file size with no visible difference on a photograph, while going below about 60% starts to show blocking around sharp edges and text. The resize slider is the blunter and usually better instrument: file size scales roughly with the number of pixels, so halving the dimensions cuts the pixel count to a quarter. A 4000-pixel-wide phone photo displayed in a 700-pixel column is carrying about thirty times more data than it needs.
Format matters too. JPEG is the right default for photographs. WebP typically produces files 25–35% smaller than JPEG at equivalent quality and is supported by every current browser. PNG is lossless, so the quality slider does nothing to it — it is the correct choice for screenshots, logos and anything with flat colour and hard edges, and the wrong choice for photos, where it can be several times larger than JPEG.
One detail worth knowing: JPEG cannot store transparency. If you convert a transparent PNG to JPEG, this tool flattens the transparent areas onto white rather than letting them turn black, which is what a naive canvas conversion produces.
How to use it
- Drop an image onto the box, or click it to pick a file. Nothing is uploaded — the browser reads it locally.
- Reduce the size slider first: most images can lose half their dimensions without anyone noticing on screen.
- Then lower quality until the preview starts to degrade, and back off one step.
- Check the saved percentage, then download the compressed file.
A worked example
A 3.4 MB photo straight off a phone, 4032 × 3024 pixels, destined for a blog post that displays it 800 pixels wide:
| Settings | Output | Size | Saved |
|---|---|---|---|
| JPEG, quality 100, full size | 4032×3024 | 2.9 MB | 15% |
| JPEG, quality 75, full size | 4032×3024 | 780 KB | 77% |
| JPEG, quality 75, 25% size | 1008×756 | 96 KB | 97% |
| WebP, quality 75, 25% size | 1008×756 | 64 KB | 98% |
The lesson is in the third row. Quality alone got the file to 780 KB; resizing to something close to the display size got it to 96 KB with no visible loss at all, because the extra pixels were never going to be shown. Switching to WebP then saved a third again.
Frequently asked questions
Does compressing an image here reduce its quality?
JPEG and WebP are lossy, so yes — detail is discarded permanently. At quality 75 that loss is invisible on a normal photograph at normal viewing size. PNG is lossless, so the quality slider has no effect on it. Always keep your original file; the tool never modifies it.
Why is my PNG barely getting smaller?
PNG is lossless, so the only saving available is from resizing. If the image is a photograph, converting it to JPEG or WebP will shrink it dramatically. If it is a screenshot or a logo, reducing dimensions is your main option — or use a dedicated PNG optimiser that reduces the colour palette.
Is there a file size limit?
There is no limit imposed by the tool, but very large images consume memory because the browser decodes them into raw pixels. A 50-megapixel photo needs roughly 200 MB of memory while it is being processed, which some phones will refuse. If a large image fails to load, that is the browser running out of memory rather than an upload failing.
Does compression remove EXIF data?
Yes. Re-encoding through a canvas discards all metadata, including GPS coordinates, camera model and timestamps. That is usually a bonus for privacy when publishing photos. If you need to keep metadata, check it first with the EXIF Viewer and record what matters before compressing.