PPT vs PPTX: File Size, Features, and Compatibility Compared

PPTX replaced PPT as the default PowerPoint format in 2007. PPTX files are up to 75% smaller, use XML internally, and support modern presentation features. PPT is a binary format from the 1990s that only older versions of PowerPoint produced by default. Unless you are opening a file from 2006 or earlier, you are working with PPTX.

File Structure

PPT stores everything in a proprietary binary format. The file is one opaque blob that PowerPoint reads sequentially. PPTX files are ZIP archives containing XML documents for slides, layouts, themes, and media. You can rename a .pptx to .zip, extract it, and inspect the XML. This makes PPTX files recoverable when corrupted (you can often fix individual slide XML), while a corrupted PPT file is usually a total loss.

File Size

PPTX files are significantly smaller than PPT equivalents. The XML content is compressed using ZIP, and images are stored more efficiently. A 20-slide presentation with photos might be 15 MB as PPT and 4 MB as PPTX. This difference adds up in corporate environments where thousands of presentations sit on shared drives and get emailed constantly.

Features

PPTX supports features that PPT cannot represent: SmartArt diagrams, modern chart types, 3D models, embedded fonts, improved animation paths, and Morph transitions. Saving a PPTX as PPT triggers compatibility warnings about features that will be lost or degraded. The reverse conversion (PPT to PPTX) preserves everything because PPTX is the superset format.

Compatibility

PPTX works in PowerPoint 2007 and later, Google Slides, Keynote, LibreOffice Impress, and all modern presentation tools. PPT is still readable by current software, but no application defaults to saving in PPT format anymore. Google Slides and Keynote both export as PPTX, not PPT. The only scenario where PPT matters is opening legacy files from old archives or systems that never upgraded.

Should You Convert?

If you have old PPT files, converting to PPTX saves storage and ensures long-term compatibility. Open the file in PowerPoint or Google Slides and save as PPTX. There is no quality loss. Going forward, always save as PPTX.

Need to share a presentation as a PDF? Our PPT to PDF converter handles both PPT and PPTX files. PDF ensures your slides look identical on any device.

Related reading: Keynote vs PPTX compares Apple and Microsoft presentation formats, DOC vs DOCX covers the same transition for Word, and XLS vs XLSX covers it for Excel. For sharing presentations, see PDF vs PPTX.