What an Image Compressor Does
An image compressor reduces the file size of a picture so it uses less disk space, less bandwidth and less memory, while trying to keep the image looking visually similar to the original. A modern phone photo can weigh 3 to 8 megabytes straight out of the camera. Compressing that same image down to a few hundred kilobytes makes it easier to attach to email, upload to a website, share on WhatsApp or embed in a document, all without any noticeable drop in quality on normal screens.
Compressed images matter for more than convenience. Page speed is a ranking signal in Google search, and Core Web Vitals (LCP in particular) are heavily influenced by image weight. A website with uncompressed hero images loses visitors on slow mobile networks. CDN costs scale with transfer size, so lighter images mean lower hosting bills. Mobile users browsing on a metered plan also appreciate not burning data on oversized photos.
How It Works Under the Hood
The tool loads your image into an HTML Image element, draws it onto a hidden canvas and then re-exports the canvas as a new image file using canvas.toBlob(). The quality parameter you pick (10 to 100 percent) controls how aggressively the chosen encoder discards information. JPG and WebP use lossy DCT and prediction-based compression that drops perceptually-invisible detail. PNG uses lossless DEFLATE compression. Everything runs on the main thread inside your browser, so the image never leaves your device.
How to Use This Tool
- Click the drop zone or drag an image file (JPG, PNG or WebP) into the browser.
- Drag the quality slider to the setting you want (80 percent is a good starting point).
- Pick an output format: JPG for smallest size, WebP for modern efficiency, PNG for lossless.
- Watch the live comparison update, showing original versus compressed byte size and percentage saved.
- Click Compress and Download to save the lighter version to your device.
- Repeat for other images or adjust settings if the preview does not look sharp enough.
Common Use Cases
- Web upload optimisation: Shrink hero banners and product photos before uploading to WordPress, Shopify or a custom site.
- Email attachments: Fit multiple images under Gmail's 25 MB attachment limit.
- Portfolio preparation: Lighten high-resolution photographs for online portfolios without visible quality loss.
- Mobile sharing: Reduce photo size before posting to WhatsApp, Telegram or Messenger on a slow connection.
- Blog thumbnails: Generate fast-loading preview images for social sharing cards.
- Storage cleanup: Compress archives of old photos to free up cloud storage.
Common Mistakes
- Compressing an already-compressed image again, which multiplies artifacts and degrades quality fast.
- Choosing a quality below 60 percent for important photos. Blocking, ringing and colour-banding become visible.
- Using JPG for logos, icons or screenshots with sharp edges. PNG or WebP preserve them better.
- Expecting EXIF data (camera, location, timestamp) to survive. Canvas re-encoding strips all metadata.
- Judging quality only on a phone screen. Always check on a bigger display before publishing.
Perceptual Quality Versus File Size
JPG and WebP are lossy: they trade a tiny bit of visual accuracy for a huge reduction in file size. At 100 percent quality the file is almost as large as the uncompressed version. At 90 percent you typically see a 50 percent reduction with no visible change. At 80 percent, another 30 percent drop. Below 60 percent, artifacts become clearly visible on flat areas like skies or faces. PNG is lossless and uses DEFLATE (the same algorithm as ZIP) to shrink file size without discarding pixels. It works wonders on screenshots and logos but is poor at compressing photographs. WebP and the newer AVIF format use smarter prediction and transform coding, generally producing files 25 to 50 percent smaller than JPG for the same quality. If your audience uses modern browsers, WebP is usually the best overall choice.
Privacy
No image is ever uploaded. The compressor runs entirely in your browser using the Canvas API, so the file stays on your device the entire time. Safe for personal photos, confidential designs and client proofs.
Frequently Asked Questions
How much size reduction can I expect?
Phone photos typically shrink by 60 to 90 percent with almost no visible quality loss. Screenshots and PNG graphics compress less because they already use fewer colours and simpler data.
What quality setting should I choose?
80 percent is a safe default for web photos. Drop to 60 percent when file size matters more than detail. Stay above 90 percent for print work or portfolio-grade images.
Does compression remove EXIF metadata?
Yes. Re-encoding through the canvas discards EXIF data such as camera model, GPS coordinates and timestamps. This is useful for privacy but inconvenient if you need to keep those details.
Which format is best for the web?
WebP gives roughly 20 to 30 percent smaller files than JPG at the same quality and is supported by every modern browser. Use JPG as a universal fallback and PNG only when you need transparency.
Can I compress multiple images at once?
This tool handles one image at a time to give you a clear side-by-side comparison. For batch work, drop one image, download, then repeat. Each run takes only a second.
Is compression reversible?
No. Lossy compression (JPG, WebP) throws away information permanently. Always keep your original file safe before compressing, because quality cannot be restored once lost.
Is my image uploaded anywhere?
No. Everything happens locally through the browser canvas API. Your image never leaves your device, which is ideal for personal photos or confidential designs.