About the Image Compressor
This image compressor shrinks a photo's file size by re-encoding it as JPEG or WebP at a quality level you choose, trading a small amount of visual detail for a much smaller download. It shows the original size, the new size and the percentage saved, so you can find the point where the file gets noticeably smaller without the image looking noticeably worse. Nothing is uploaded — the re-encoding happens locally using the Canvas API.
How to use the Image Compressor
- 1
Upload the image you want to shrink.
- 2
Choose JPEG for maximum compression or WebP for a smaller file at similar quality.
- 3
Drag the quality slider and watch the file size estimate update in the Details panel.
- 4
Download once you are happy with the balance between size and visual quality.
What people use it for
Speeding up a website
Unoptimised photos are the single biggest cause of slow-loading pages. Compressing hero images and thumbnails before uploading them can cut page weight by 60-90%.
Fitting an email attachment limit
Most mail providers cap attachments around 20-25 MB. Compress a batch of photos individually to get each one under the limit without losing the ability to view them clearly.
Saving storage or bandwidth
Compressing a photo library before backing it up, or before sending it over a metered connection, can meaningfully reduce the data transferred.
Why quality 70-80% is usually the sweet spot
JPEG and WebP compression work by discarding information the human eye is least likely to notice, particularly fine colour detail, which our vision is less sensitive to than fine brightness detail. At high quality settings, 90% and above, the file barely shrinks because little is being discarded. Between roughly 60% and 80%, file size drops sharply while visible quality loss stays minimal for most photos. Below 50%, compression artefacts become obvious: blocky patches around sharp edges, smudged text, and colour banding in smooth gradients like skies. There is no universally correct number — a photo with lots of fine texture tolerates lower quality settings better than a photo with large flat areas or text.
Why compressing a PNG barely helps
PNG is a lossless format: it never discards image data, so there is no quality slider that trades fidelity for size the way JPEG has. A PNG's file size is determined almost entirely by how compressible its pixel data is, which mostly comes down to how much flat colour and repetition the image contains. A screenshot of a simple UI compresses beautifully as PNG; a detailed photograph does not, often producing a file several times larger than the same photograph saved as JPEG. If a PNG source needs to shrink substantially, converting it to JPEG or WebP first, accepting the format's lossy compression, is usually the only way to get a meaningfully smaller file.
Tips
- WebP typically produces a smaller file than JPEG at the same visual quality, but check your target platform supports it before relying on it exclusively.
- Compress a copy, not your only copy — quality lost this way cannot be recovered later.
- If an image already looks compressed (visible blockiness), recompressing it again will only make it worse, not better.