Overview
Introduction
This tool compresses a JPG down using one of three straightforward presets, entirely in your browser, so you don't have to guess a specific quality number.
It reports the exact before-and-after file size and percentage saved so the result is concrete rather than a guess.
What Is JPG Compressor?
A client-side JPEG compressor that re-encodes an uploaded image through the browser's real JPEG encoder at one of three fixed quality presets: High (0.85), Medium (0.55), or Low (0.25).
It's aimed at people who want a quick, confident compression decision rather than fine-tuning a continuous slider.
How JPG Compressor Works
Selecting a preset resolves it to a real 0-1 JPEG encoder quality value, which the component passes to canvas.toBlob("image/jpeg", quality); the resulting blob's actual byte size is measured and compared against the original.
The compressed blob is decoded back into pixels so the preview shows the genuine compressed result, artifacts and all, rather than the untouched original.
When To Use JPG Compressor
Use it when you need a JPG smaller fast, without wanting to think about a quality percentage: pick Medium as a safe default, or Low when file size matters more than fidelity.
It's a good fit for batch-style workflows where consistent, predictable presets matter more than per-image fine-tuning.
Often used alongside JPG Quality Changer, JPG Optimizer and PNG Compressor.
Features
Advantages
- Performs a genuine JPEG re-encode with real, measured file-size results.
- Three clear presets remove the guesswork of picking a specific quality number.
- Runs entirely client-side; your image is never uploaded anywhere.
Limitations
- Only three fixed quality stops are offered; use the Quality Changer if you need a specific in-between value.
- Doesn't resize dimensions or strip metadata; it only changes JPEG encoding quality.
Examples
Best Practices & Notes
Best Practices
- Start with Medium and only drop to Low if the resulting file is still too large for your use case.
- Check the preview at each preset before downloading, since compressibility varies a lot by image content.
Developer Notes
resolveJpgCompressionPreset validates the source buffer and resolves a JpgCompressionPreset ('high'|'medium'|'low') to its fixed 0-1 quality constant from JPG_COMPRESSION_PRESETS; the actual canvas.toBlob encode and decode-back happen in the component, same DOM-boundary split as jpg-quality-changer.
JPG Compressor Use Cases
- Shrinking photos for a website or CMS with upload size limits
- Preparing images for email attachments
- Quickly reducing storage footprint for a batch of photos
Common Mistakes
- Reaching for Low when Medium would already meet your size target with noticeably better quality.
- Expecting dimension changes: this tool only affects encoding quality, not width/height.
Tips
- Combine with the JPG Resizer beforehand if your real goal is a much smaller file and the image is larger than you need.
- Use the reported percentage-saved number to decide whether a lower preset is actually worth the visible quality tradeoff.