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Compress PPT files

Options for old PowerPoint 97–2003 presentations: a compressed ZIP or conversion to PPTX.

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How to compress PPT files

  1. Add your files

    Drop files on the box, paste them or choose them from your device. Nothing is uploaded.

  2. Check the settings

    The default preset suits most files. Change quality, size or format if you need a smaller file.

  3. Download the result

    Save each file or all of them as one ZIP. If a file cannot get smaller, you keep the original.

The PowerPoint 97–2003 format

A .ppt file is a presentation in the binary format PowerPoint used from version 97 until 2003. Like old Word and Excel files, it is a Compound File Binary container, here with a "PowerPoint Document" stream of binary records for slides, text and shapes, and a separate "Pictures" stream that holds every image. Since PowerPoint 2007 the default is PPTX, but .ppt files survive in lecture archives, training material, conference talks from the 2000s and templates that are still being reused.

A related format, .pps, is the same file set to start as a slide show. Everything on this page applies to it too.

What fills up a .ppt

  • Pictures. The Pictures stream stores images more or less as they were inserted, often as uncompressed bitmaps for anything that was pasted from the clipboard.
  • Cropped areas. When you crop a picture, PowerPoint keeps the entire original image so you can undo the crop later, unless someone ran Compress Pictures with the option to delete cropped areas.
  • Embedded objects. Charts and tables from Excel, equations and embedded fonts carry their own data.
  • Linked media. Videos and sounds in .ppt files are usually linked, not embedded; the size problem appears when you send the folder with the media files along.

Options for a .ppt file

The tool does not rewrite binary presentations: the record structure is intricate, and a partially damaged .ppt may open with missing slides or images, which you might only notice in front of an audience. You get two safe choices:

  1. Maximum ZIP compression of the original. Good when the file must stay a .ppt, for example for an old projector computer or a learning platform that expects it. Savings depend on the content: uncompressed bitmaps shrink well, JPEG photos hardly at all.
  2. Save as PPTX, then compress. Open the file in PowerPoint, choose File › Save As › PowerPoint Presentation (.pptx), or open it in LibreOffice Impress or Google Slides and download as PPTX. The PowerPoint compressor then recompresses the pictures inside. This usually gives the much smaller result.

Tips for old presentations

  • After converting, check slides with WordArt, old animations and embedded objects; they may look slightly different in current versions.
  • Collect linked videos and sounds before converting: open the presentation, check that media plays, and insert missing files again from their folder.
  • If the presentation is only for reading, export it to PDF and compress that with the PDF compressor. A PDF opens on every device without PowerPoint.
  • Keep the original .ppt until you have checked the converted version from the first slide to the last.

PPT questions

Why can't the tool compress the pictures inside my .ppt?

Replacing images inside the binary format requires rewriting offsets throughout the file. In a browser this cannot be done reliably for every version of the format, so the tool does not risk it.

What is the difference between .ppt and .pptx?

PPT is the binary format of PowerPoint 97–2003; PPTX is the ZIP-based XML format used since 2007. PPTX is usually smaller, more robust and supported by all current software.

Will animations survive the conversion to PPTX?

Standard entrance, exit and emphasis effects and slide transitions convert well. Very old effects may be replaced by the nearest modern equivalent.

Can I open a .ppt without PowerPoint?

Yes. LibreOffice Impress, Google Slides and Keynote on the Mac open .ppt files and can save them in modern formats.

Related pages

The other legacy formats are covered on the DOC and XLS pages. All document tools are on the document compressor page, and how it works explains what happens to your files.