CONVERT PPT → PPTX (PPT to PPTX)
Upgrade legacy PowerPoint 97-2003 files to modern PPTX format.
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HOW TO CONVERT PPT → PPTX
Upload the PPT
Drop your legacy PowerPoint deck.
Convert via LibreOffice
LibreOffice Impress opens the binary PPT and writes a standards-compliant PPTX.
Download the PPTX
Grab the modern deck — slides, transitions and master layouts preserved.
Converting PPT to PPTX modernises a legacy PowerPoint binary deck into the XML-based Office Open format every current PowerPoint, Keynote and LibreOffice Impress handles natively. The PPTX supports modern animations, smart-art, co-authoring and is much smaller than the equivalent PPT.
Why convert PPT to PPTX
PowerPoint switched to PPTX in 2007. Legacy PPT files still open but trigger compatibility warnings and lose access to features added in the last 15 years. Converting brings old decks into the modern format for collaborative editing, richer animations and better cross-platform rendering.
PPT vs PPTX — Technical specifications
Side-by-side comparison of the technical details.
PPT
- MIME type
- application/vnd.ms-powerpoint
- Container
- OLE Compound File
- Successor
- .pptx (2007)
- Default slide size (1997-2003)
- 720×540 px (4:3)
- MIME Type
- application/vnd.ms-powerpoint
- Extension
- .ppt
- Category
- Presentations
- Full Name
- PowerPoint Presentation (Legacy)
- Conversion Engine
- LIBREOFFICE
PPTX
- MIME type
- application/vnd.openxmlformats-officedocument.presentationml.presentation
- Container
- ZIP (Office Open XML)
- MIME Type
- application/vnd.openxmlformats-officedocument.presentationml.presentation
- Extension
- .pptx
- Category
- Presentations
- Full Name
- PowerPoint Presentation
- Conversion Engine
- LIBREOFFICE
- Standard
- ISO/IEC 29500, ECMA-376
- Released in
- Microsoft Office 2007
- Legacy predecessor
- .ppt (binary OLE, 1987-2007)
| Specification | PPT | PPTX |
|---|---|---|
| MIME type | application/vnd.ms-powerpoint | application/vnd.openxmlformats-officedocument.presentationml.presentation |
| Container | OLE Compound File | ZIP (Office Open XML) |
| Successor | .pptx (2007) | — |
| Default slide size (1997-2003) | 720×540 px (4:3) | — |
| MIME Type | application/vnd.ms-powerpoint | application/vnd.openxmlformats-officedocument.presentationml.presentation |
| Extension | .ppt | .pptx |
| Category | Presentations | Presentations |
| Full Name | PowerPoint Presentation (Legacy) | PowerPoint Presentation |
| Conversion Engine | LIBREOFFICE | LIBREOFFICE |
| Standard | — | ISO/IEC 29500, ECMA-376 |
| Released in | — | Microsoft Office 2007 |
| Legacy predecessor | — | .ppt (binary OLE, 1987-2007) |
PPT vs PPTX — Strengths and limitations
What each format does best, and where it falls short.
PPT Strengths
- Universal legacy compatibility since 1987.
- Binary format loads quickly on older hardware.
- Preserves animations, transitions, and embedded media.
- Every modern presentation tool can open it.
Limitations
- Deprecated since 2007 — PPTX is the recommended format.
- Animations and SmartArt often render differently outside PowerPoint 2003.
- Macro-enabled variants are a malware vector.
PPTX Strengths
- ~75% smaller than the legacy binary .ppt thanks to ZIP compression.
- Human-readable XML inside — easy to script, patch, or diff.
- Cross-compatible with Keynote, Google Slides, LibreOffice Impress (with minor drift).
- Preserves master slides, themes, animations, notes, and embedded media.
- ISO/IEC 29500 standardized — vendor-independent on paper.
Limitations
- Animations and transitions often render differently outside Microsoft PowerPoint.
- Embedded fonts and media balloon file sizes rapidly.
- Complex layouts drift subtly when round-tripped through non-Microsoft editors.
Quality & Compatibility
Standard slide content (text, shapes, images, tables) transfers losslessly. Complex animations and slide transitions may render slightly differently; ancient WordArt and legacy OLE objects sometimes require manual re-creation in the PPTX.
Tips for Best Results
- Preview the first few slides before relying on the PPTX — animation timings occasionally shift during conversion.
- Custom fonts embedded in the PPT survive; otherwise standard PowerPoint fonts substitute.
Frequently Asked Questions
Yes. The free tier accepts files up to 25 MB without registration, email capture or watermarks; paid plans go up to 2 GB. Paid plans raise the size cap, enable batch conversions and provide a REST API for automation, but nothing on the free tier is quality-limited — the output is exactly the same as on any paid plan.
Standard animations and transitions transfer; exotic custom effects occasionally render differently. Preview the output before production use — for critical decks, rebuild any transitions that look off in the target PowerPoint version.
Uploads run over HTTPS, files are processed in isolated containers, and both the source PPT and the PPTX output are auto-deleted within two hours. No account is required, file contents are never logged, and KaijuConverter does not use uploads for AI training. The paid plan adds a signable data-processing agreement for regulated workflows.
Typically 30-40% smaller than the source PPT, thanks to XML/ZIP compression. For image-heavy decks the savings are smaller because embedded images dominate file size.
Most files finish in well under a minute. Small images and documents are typically ready in a few seconds; large video or audio files scale roughly with duration. Upload speed from your network is usually the dominant factor, not server time.
No. PPTX is an ISO standard supported by PowerPoint, Keynote, Google Slides, LibreOffice Impress, OnlyOffice and most other presentation tools.
PowerPoint Presentation (Legacy)
Source formatPPT is the legacy binary format for Microsoft PowerPoint 97-2003 presentations. Many archived presentations and templates still use this format and require conversion for modern editing.
PowerPoint Presentation
Target formatPPTX is the modern Microsoft PowerPoint format based on Open XML. It is the standard for business and educational presentations, supporting slides, animations, transitions, and embedded media.
Common Use Cases
Legacy deck modernisation
Archive decks from pre-2007 become PPTX for ongoing use in current PowerPoint.
Google Slides and Keynote
Both handle PPTX natively; PPT imports often strip formatting or animations.
Co-authoring features
Real-time collaboration in PowerPoint 365 requires PPTX; PPT decks need upgrade first.
PPT vs PPTX — Typical file sizes
Approximate file sizes for common scenarios.
- Simple text deck (10 slides) 100-500 KB
- Typical corporate deck with images 2-15 MB
- Simple 10-slide deck (text only) 50-200 KB
- Typical corporate deck with images (30 slides) 2-20 MB
- Deck with embedded 4K videos 100-500 MB
Sensitive Documents, Scanned OCR, or 500+ Pages?
For legally sensitive archives that must never leave your local network, or multi-hundred page scanned PDFs needing optical character recognition, local document workstations ensure full compliance.
One-time payment with zero recurring commitment: convert files up to 1 GB, OCR, PDF/A, and .ZIP batches for 24 hours.
Full 7 days of unlimited conversions, up to 2 GB per file, 100% ad-free with zero subscription.
High-throughput enterprise pipeline for files up to 2,048 MB, 50-file batches, ISO PDF/A, and priority processing.
Offline conversion for multi-hundred page contracts, spreadsheets, and local optical extraction.
High-accuracy legal OCR, certified PDF/A archiving, and compliant document redaction.
Related comparisons
See these formats side by side to understand which fits your use case best.
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