How We Compress Office Documents
Modern Office documents (DOCX and PPTX) are actually ZIP archives containing XML files and embedded media. The biggest contributor to file size is usually embedded images—photos, screenshots, and graphics inserted into your documents.
Our compression focuses on optimizing these embedded images using the same techniques as our standalone image compressors, while leaving text, formatting, and document structure completely untouched.
What Gets Compressed
- Embedded images: Photos, screenshots, and graphics are recompressed
- JPEG images: Re-encoded with MozJPEG for smaller files
- PNG images: Optimized with smart palette reduction (never converted to JPEG, preserving sharp edges)
- Oversized images: Downsampled if resolution exceeds document needs
Note: Very small images (under 5 KB) are skipped to avoid processing overhead.
What We Preserve
- All text and formatting — Fonts, styles, and layout unchanged
- Charts and SmartArt — Vector graphics remain crisp
- Tables and layouts — Structure fully preserved
- Animations and transitions — PowerPoint effects work normally
- Hyperlinks and references — Links remain functional
- Comments and tracked changes — Review features preserved
Expected Results
Compression results depend entirely on how many images are embedded in your document:
| Document Type | Typical Savings |
|---|---|
| Photo-heavy presentations | 50-80% |
| Documents with screenshots | 40-60% |
| Mixed content (text + images) | 20-40% |
| Text-heavy documents | 5-20% |
| Already optimized files | 0-10% |
Supported Formats
| Application | Supported | Not Supported |
|---|---|---|
| Word | .docx (Office 2007+) | .doc (legacy) |
| PowerPoint | .pptx (Office 2007+) | .ppt (legacy) |
Note: Legacy formats (.doc, .ppt) use a binary format that doesn't support the same optimization techniques. If you need to compress legacy files, first save them as .docx or .pptx in Microsoft Office.