Image Compressor - Reduce Image File Size Online
How to Compress Images Online
Upload one or more images by dragging them onto the upload area or clicking to browse. Adjust the quality slider to control compression strength — lower values produce smaller files. Optionally set a maximum width to resize large images. Click Compress and download the optimized files individually or all at once.
This tool accepts JPEG, PNG, and WebP images up to 50MB each. Multiple files can be processed in a single batch, and each file retains its original format after compression.
Why Image Compression Matters for Web Performance
Image weight is the single largest contributor to page size on most websites, accounting for an average of 50% or more of total page bytes. Unoptimized images slow down page load times, increase bandwidth costs, and degrade the user experience on mobile connections.
Core Web Vitals and Image Size
Google uses Core Web Vitals as a ranking signal, and image optimization directly impacts two of the three metrics. Largest Contentful Paint (LCP) measures how quickly the largest visible element loads — typically a hero image or banner. Reducing that image from 2MB to 200KB can shave seconds off the LCP score. Interaction to Next Paint (INP) also benefits because smaller page weight means the browser has more resources available for processing user interactions instead of downloading and decoding large images.
JPEG Compression Explained
JPEG compression works by dividing the image into 8x8 pixel blocks and applying a mathematical transformation (discrete cosine transform) to each block. The quality setting determines how aggressively the transform coefficients are quantized — higher quantization discards more data, producing smaller files with more visible block artifacts. At quality 80, the quantization is mild enough that artifacts are imperceptible at normal viewing distances.
A common mistake is re-compressing an already-compressed JPEG multiple times. Each pass introduces additional quality loss (generation loss), so it is best to compress from the highest quality source available. If you have the original uncompressed image, start from that rather than from a previously compressed version.
PNG Compression Characteristics
PNG uses lossless compression (DEFLATE), meaning no image data is lost during compression. Because of this, the quality slider has no effect on PNG files in this tool. The primary way to reduce PNG file size is to resize the image using the max width setting, or to convert it to WebP format using the Image to WebP Converter. For photographs, PNG is rarely the right format — JPEG or WebP will produce dramatically smaller files.
WebP Quality Settings
WebP supports both lossy and lossless modes. When compressed with this tool, WebP images use lossy compression controlled by the quality slider, just like JPEG. WebP typically achieves 25-35% smaller files than JPEG at equivalent visual quality, making it the preferred format for modern websites.
Recommended Settings by Use Case
| Use Case | Quality | Max Width | Expected Savings |
|---|---|---|---|
| Blog post photos | 75-80 | 1200px | 40-60% |
| E-commerce products | 80-85 | 1600px | 30-50% |
| Thumbnails & cards | 60-70 | 600px | 50-70% |
| Hero/banner images | 80-85 | 1920px | 30-50% |
| Email images | 70-75 | 800px | 45-65% |
| Social media | 80-85 | 1080px | 30-45% |
Batch Compression Workflow
For sites with many images, upload all files at once, set a consistent quality level and max width, and compress them in one batch. The results table shows the savings for each file and the total savings across the entire batch, letting you quickly gauge the impact before downloading.
Client-Side Privacy
This compressor runs entirely in your browser using the HTML5 Canvas API. Your images are never uploaded to any server, making it safe for compressing screenshots, internal documents, and confidential photos. No data leaves your device at any point during the process.
Related Tools
- Image to WebP Converter - Convert images to WebP format for even smaller sizes
- SVG Optimizer - Optimize vector graphics for the web
Frequently Asked Questions
What is the difference between lossy and lossless compression?
Lossy compression permanently removes some image data to achieve smaller file sizes. JPEG and WebP use lossy compression controlled by a quality slider — lower quality means smaller files with more visible artifacts. Lossless compression reduces file size without discarding any data, preserving pixel-perfect quality. PNG uses lossless compression, so reducing a PNG with this tool relies on resizing rather than quality reduction.
What quality setting should I use for web images?
For most website photos in JPEG or WebP format, a quality setting between 70 and 85 provides the best balance of file size and visual quality. At quality 80, compression artifacts are nearly invisible to most viewers while achieving 30-50% file size reduction. For thumbnails or background images where fine detail matters less, quality 50-70 works well. For high-resolution portfolio or product photography, use quality 85-95.
Will compressing an image reduce its visual quality?
For JPEG and WebP images, yes — compression reduces quality proportionally to the file size savings. However, at moderate quality settings (70-85), the quality loss is difficult to perceive in typical viewing conditions. PNG images are lossless, so this tool only reduces PNG size through resizing. If you need lossless size reduction, consider converting to WebP at quality 100.
How does the max width setting work?
The max width setting resizes images that are wider than the specified pixel value while maintaining the original aspect ratio. For example, setting max width to 1200px will resize a 4000x3000 image to 1200x900. Images already smaller than the max width are left unchanged. This is useful for preparing images for web use where ultra-high resolutions are unnecessary and waste bandwidth.