Need to reduce a photo from 5MB to under 200KB for your website, or resize an image for social media? Upload it here and adjust quality, dimensions, and format — all processing happens on your device, not a remote server.
Last Updated: May 8, 2025Privacy: 100% Local Browser Processing
What is the Image?
An Image Compressor reduces image file sizes directly in your browser using the HTML5 Canvas API — no upload to any server required. It supports JPEG, PNG, and WebP formats with adjustable quality, custom dimensions, and aspect ratio locking. This is essential for optimizing images for web performance, email attachments, social media posts, and documentation.
How to Use
- 1Drag and drop an image or click Select Source Image to upload.
- 2Adjust the output dimensions (width and height) as needed.
- 3Lock aspect ratio to prevent distortion when resizing.
- 4Choose the output format (JPEG, PNG, or WebP).
- 5Adjust the quality slider to control compression level.
- 6Preview the result and download the optimized image.
Pro Tips & Best Practices
- For web images, a JPEG quality of 75-80% is the sweet spot — it reduces file size by 60-70% with virtually no visible quality loss for photographs.
- Use WebP format whenever possible — it produces significantly smaller files than JPEG and PNG while maintaining the same visual quality. All modern browsers support it.
- When resizing, always lock the aspect ratio to prevent the image from appearing stretched or squashed. Unlock only if you intentionally need a specific non-proportional size.
- For PNG images with large areas of solid color (logos, icons, diagrams), the savings from quality reduction are minimal — consider converting to SVG instead for the smallest possible size.
Real-World Use Cases
- Web performance optimization — compress hero images, product photos, and thumbnails to improve Largest Contentful Paint (LCP) scores and page load times.
- Email attachments — reduce photo sizes to fit within email attachment limits (typically 10-25MB) without noticeable quality loss.
- Social media — resize and compress images to match platform-specific requirements (Instagram: 1080x1080, Twitter: 1200x675, LinkedIn: 1200x627).
- Documentation — optimize screenshots and diagrams for inclusion in technical documentation, reducing overall document size.
Technical Deep Dive
Image compression works by re-encoding the image through the HTML5 Canvas API — a powerful browser-native graphics engine. When you upload an image, the tool draws it onto an invisible canvas element, optionally resizing it to your specified dimensions. It then calls canvas.toBlob() or canvas.toDataURL() with the target format and quality parameter to produce the compressed output. For JPEG and WebP, the quality parameter (0 to 1) controls the compression ratio — lower values produce smaller files with more artifacts. For PNG, the output is always lossless, but resizing a large image to smaller dimensions inherently reduces file size. The tool calculates the compression ratio and shows both the original and compressed file sizes so you can make an informed tradeoff between quality and size. WebP format typically produces 25-35% smaller files than JPEG at the same visual quality, making it the preferred format for modern web applications. The aspect ratio lock feature ensures that changing the width automatically adjusts the height (and vice versa) to prevent distortion.