Image Compressor
Image compressor: shrink JPG, PNG and WebP images in your browser, with quality, resizing and format conversion. Free, no sign-up, and it runs in your browser.
Dedicated page: /en/image-compressor
JPG, PNG, WebP, GIF or BMP. The image is processed on your device and never uploaded.
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Quick answer
An image compressor reduces the file size of JPG, PNG and WebP images by re-encoding them at a quality you choose, with optional resizing. Smaller images load faster, rank better and cost less to host, and here compression happens in your browser: images are never uploaded.
About this Image Compressor
Image compressor: shrink JPG, PNG and WebP images in your browser, with quality, resizing and format conversion. It is one of the Image and Media on ToolUstad, and like every tool here it runs entirely in your browser: nothing you type, paste or open is uploaded to a server, and there is no sign-up or usage limit.
What is image compression?
Image compression shrinks the number of bytes an image needs. Lossy compression, used by JPG and WebP, discards detail the eye barely notices and can cut 70 to 90 percent of the size. Lossless compression, used by PNG, rearranges the data without losing any, saving less. This tool re-encodes your image on a canvas in your browser at your chosen quality and dimensions, then shows the honest before and after numbers.
Which format should you choose?
| Format | Best for | Notes |
|---|---|---|
| JPG | Photos | No transparency; quality 75 to 85 is the sweet spot |
| WebP | Photos and graphics for the web | Typically 25 to 35 percent smaller than JPG at equal quality |
| PNG | Screenshots, logos, transparency | Lossless and larger; use only when quality or alpha matters |
Why image size matters
- Page speed: images are usually the largest part of a web page and drive Largest Contentful Paint.
- SEO: faster pages rank better, and Google measures real user speed through Core Web Vitals.
- Uploads: marketplaces, forms and email all reject or punish oversized attachments.
- Storage and bandwidth: smaller libraries cost less to host and back up.
Best practices
- Resize to the size the image will actually display: a 4,000 px photo in a 700 px slot wastes bytes.
- Use quality 75 to 85 for photos: below that, artefacts appear; above it, size grows for little gain.
- Compress once from the original: recompressing a compressed JPG stacks the damage.
- Keep the original file archived in case you need full quality later.
Common mistakes to avoid
- Uploading camera originals straight to a web page.
- Converting simple graphics to JPG, which makes text edges fuzzy and can grow the file.
- Compressing images that are already optimised and wondering why they got bigger.
- Forgetting that transparency needs PNG or WebP: JPG fills it with a solid background.
Who is the image compressor for?
Bloggers, e-commerce sellers, web designers and anyone whose upload was rejected for size. Server based compressors require uploading private photos to a stranger's machine and often queue free users; this compressor runs locally, so family photos, product shots and documents are processed on your own device and never transmitted.
A realistic before and after
A typical phone photo arrives at 4,032 x 3,024 pixels and about 3.8 MB. Displayed in a blog layout 800 pixels wide, it needs none of that bulk: resized to 1,600 pixels wide for retina screens and saved as WebP at quality 80, the same image usually lands between 180 and 320 KB, over 90 percent smaller, with no visible difference in the article. That single habit, repeated across a site, is routinely the difference between a page that passes Core Web Vitals and one that fails on mobile, which is why compressing here, before upload, beats any plugin that cleans up afterwards.
Learn: how to use the Image Compressor
- Drop an image onto the box or click to choose one. A preview and the original size, dimensions appear instantly.
- Move the quality slider (80% is the sweet spot for photos), set a maximum width or height if you need smaller dimensions, and pick the output format.
- Compare the compressed size and saving, then download. Settings re-compress live as you change them.
Features
- Quality slider from 5% to 100% with live re-compression
- Resize by maximum width and height, with aspect ratio lock
- Convert between JPEG, WebP and PNG (JPEG flattens transparency onto white)
- Side-by-side original and compressed previews with sizes and dimensions
- Saved percentage shown honestly, including when a file grows because the original was already efficient
- Drag and drop, keyboard accessible file picker, works with photos from your phone
Worked example
A 4.2 MB phone photo at 4032 x 3024, capped at 1600 px wide and saved as JPEG at 80% quality, typically lands near 380 KB: about a 91% saving, with no visible quality loss on a web page.
Frequently asked questions
Is my image uploaded to a server for compression?
Never. Compression uses the canvas built into your browser, on your device. You can prove it: load this page, go offline, and the tool still works.
Which format should I choose?
WebP for websites (smallest, supports transparency), JPEG for maximum compatibility with photos, PNG only when you need lossless quality or crisp transparency and accept a bigger file.
Why did my PNG get bigger as a JPEG... or smaller file grow?
An already-optimised image, or a simple graphic saved as PNG, can grow when re-encoded. The stats show the honest result either way; lower the quality or keep the original in that case.
What quality setting is best?
75 to 85% for photos on the web: the file shrinks dramatically while the difference stays invisible at normal viewing sizes. Go lower only for thumbnails.
Will compression reduce image quality?
Lossy compression always discards some data, but at quality 75 to 85 the difference is invisible at normal viewing sizes for photographs. Compare the preview before downloading, and raise the quality if you see artefacts in detailed areas.
Why did my image get bigger after compression?
If the file was already well optimised, or it is a simple graphic better suited to PNG, re-encoding can add bytes. The tool shows the true result either way; keep the smaller of the two files.
Are my images uploaded to a server?
No. The compression uses your browser's canvas processing on your own device. You can confirm it by loading the page, going offline, and compressing: it still works.
Related tools
More Image and Media like this one, plus two picks from other categories. Each opens its own dedicated page.