What This Tool Does
This image compressor reduces file size of JPG, PNG, and WebP images using a quality slider. Everything runs in your browser using the Canvas API, so your images are never uploaded to any server. Compare original vs compressed file size and download the optimized version with one click.
Inputs Explained
- Image File: Upload JPG, PNG, or WebP image (up to 20 MB).
- Quality: 0 to 100 — lower means smaller file but lower visual quality.
- Output Format: JPG (smallest for photos), WebP (modern, best balance), or PNG (lossless).
- Max Width: Optional — resize during compression for extra savings.
How It Works
The image is loaded into a Canvas element, re-encoded at your chosen format and quality using canvas.toBlob(). JPG and WebP use lossy compression — lower quality drops detail to shrink the file. PNG is lossless but benefits from format conversion when the image is photographic. No server upload happens at any point.
Formula / Logic Used
Image Compressor
Compress JPG, PNG, and WebP images right in your browser — no upload required.
Step-by-Step Example
Typical savings:
- JPG photo at 90 quality → 70 quality: 35-50% smaller, barely noticeable.
- PNG photo → JPG at 85 quality: 60-85% smaller (huge — PNG is wasteful for photos).
- JPG → WebP at same quality: 25-35% smaller with equal visual quality.
- 4K photo resized to 1920 wide: additional 70% reduction on top of compression.
Use Cases
- Website optimization: Shrink images before uploading to reduce page load times and improve Core Web Vitals.
- Email attachments: Compress photos to fit under Gmail/Outlook 25 MB attachment limits.
- Social media: Pre-compress images so the platform's auto-compression doesn't destroy quality.
- WordPress uploads: Avoid hitting PHP upload size limits by pre-compressing large photos.
- Storage space: Reduce disk usage for large photo collections, especially for cloud storage.
Assumptions and Limitations
- Maximum file size depends on your browser's memory — typically 20-50 MB works reliably.
- WebP support requires a modern browser (Chrome, Firefox, Safari 14+, Edge). Not available in Safari 13 or older.
- Very aggressive compression (quality below 40) causes visible artifacts, especially on gradients and text.
- PNG compression here re-encodes with Canvas — for maximum PNG size reduction, specialized tools like pngquant or tinypng offer better results.
Frequently Asked Questions
Is my image uploaded to a server?
No. All compression happens in your browser using the Canvas API. Your image never leaves your device. You can even use this tool offline once the page has loaded.
What quality setting should I use?
For photos: 75-85 is usually invisible to the eye, 60-70 is fine for web. Below 50 shows visible artifacts. For graphics with text: use 85+ or switch to PNG/WebP lossless. Always compare original vs compressed before saving.
Why is WebP smaller than JPG?
WebP uses more modern compression (based on VP8) that finds better ways to encode similar image data. At the same visual quality, WebP files are typically 25-35% smaller than JPG. All modern browsers support WebP.
Will compression lose image quality?
JPG and WebP are lossy — some quality is always lost, but at 80-90 quality the loss is invisible to most viewers. PNG compression is lossless but produces larger files. Choose based on your quality vs size needs.
Can I compress multiple images at once?
This tool handles one image at a time. For batch compression of many files, use a desktop tool like ImageOptim (Mac), FileOptimizer (Windows), or tinypng.com for bulk work.
Why is my PNG bigger after compression?
Canvas re-encoding can sometimes produce a slightly larger PNG if the original was already well-optimized. For PNG-heavy workflows, convert to JPG (for photos) or WebP (for everything) to get real savings.
Does this work for GIFs?
Static GIFs can be compressed but will lose animation. For animated GIFs, use specialized tools. Converting GIFs to WebP or MP4 typically gives massive size reductions with better quality.
What's the best format for web images?
WebP is best for modern browsers (25-35% smaller than JPG at same quality). JPG is the safe universal choice for photos. PNG is best for graphics with transparency or sharp edges. AVIF is even better than WebP but has less browser support in 2025.
Sources and References
- MDN — HTMLCanvasElement.toBlob — Canvas API used for image compression.
- WebP — Google Developers — Official WebP format documentation and compression advantages.
- web.dev — Choose the Right Image Format — Google's guide to image optimization for the web.
- MDN — Image file type and format guide — Comparison of JPG, PNG, WebP, AVIF and other image formats.