How-To Guide
🗜️ Compress Tool Guide
Compress images and PDF files — reduce file size while preserving quality. All processing is local; files are never uploaded.
Step-by-Step Instructions
1
Choose a file type — Click the tabs at the top to select Images or PDF mode.
2
Drag in your file(s) — Drop images or a PDF file onto the upload area. Image mode supports batch compression for multiple files at once.
3
Adjust the compression level — Drag the slider to set compression strength (10%–95%). Lower values mean more aggressive compression, smaller file size, and greater quality loss.
Recommended: 70% for images | PDF mode uses built-in optimization algorithms (slider not applicable)
Recommended: 70% for images | PDF mode uses built-in optimization algorithms (slider not applicable)
4
Click Compress — A side-by-side comparison shows original vs. compressed file sizes. Click to download the compressed file.
Compression Level Reference
| Level | Image Quality | Size Reduction |
|---|---|---|
| 90% | Near-lossless | ~10%–20% |
| 70% (Recommended) | Visually indistinguishable | ~40%–60% |
| 50% | Minor quality loss | ~60%–75% |
| 30% | Noticeable compression artifacts | ~75%–85% |
| 10% | Heavily compressed | ~85%+ |
Pro Tips
- Website image optimization: Use the 70% level for JPEG/PNG images to strike a great balance between quality and page load speed.
- PDF slimming: Best suited for PDFs containing high-resolution images. Text-only PDFs see limited reduction since the text is already compact.
- Batch compression: In image mode, drop multiple files at once and apply the same compression setting to all — great for bulk work.
✅ Tip: For even smaller files, convert images to WebP format first using the Image Converter, then compress. This two-step approach yields the smallest possible file sizes.
⚠️ Note: PDF compression uses the pdf-lib library and primarily shrinks embedded image resources. If your PDF is mostly text, compression gains will be minimal.