Convert PPT to PPTX
The .ppt format is PowerPoint's binary from before 2007. It is large, opaque, and treated with suspicion by mail systems because of its long association with macro-borne malware. Converting to .pptx keeps the slides and the formatting while making the file smaller, inspectable and far easier to send.
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What it does
- Slides, text, images and layouts are carried across
- Output is a ZIP of XML rather than an opaque binary
- Typically several times smaller than the original
How to use PPT to PPTX
- 1
Upload the .ppt
Any legacy binary deck, including ones written by software other than PowerPoint.
- 2
The deck is repackaged
Slides, masters, shapes and text are written into the Office Open XML structure. Nothing is flattened to images.
- 3
Check fonts and any macro-driven behavior
A plain .pptx cannot store macros, and a deck built around a very old font may reflow if that font is missing.
How it works
The compound binary is opened and its presentation model — slides, masters, layouts, shapes, text and embedded media — is written into the Office Open XML package that .pptx uses. The package is a ZIP with one XML part per slide plus the shared resources.
This is a re-encoding rather than a rendering, so shapes stay shapes and text stays editable. Nothing becomes a picture.
The three reasons to leave .ppt
Size. The binary format stores media raw and its structure uncompressed. The same deck in the newer format is routinely three to five times smaller, which is the difference between an email that sends and one that bounces.
Opacity. A compound binary cannot be inspected or repaired without PowerPoint. A .pptx unzips into readable XML, which matters when a file is damaged or when an archive needs to know what is inside it.
Suspicion. The legacy format's association with macro-borne malware means mail gateways and document systems frequently quarantine it. The plain new format cannot execute anything, and is treated accordingly.
What to check afterwards
Fonts first. Old decks were laid out around typefaces that may not be installed any more, and a substitution changes line breaks, which can push text out of its box. Page through the deck once at full size.
Then any embedded media. Very old audio and video formats sometimes need re-linking after conversion, and it is easier to notice now than during a presentation.
Why the file gets so much smaller
An old .ppt frequently shrinks by half or more, and the reason is structural
rather than a compression setting.
The binary format stored images in a fairly raw form and kept a great deal of
editing history, undo state and orphaned objects that nobody could see. A .pptx
is a ZIP archive, so everything inside it is compressed as a matter of course, and
the conversion writes only what the deck currently contains.
The other practical gain is delivery. Corporate mail filters and upload forms have
grown suspicious of the old binary Office formats, because macro-carrying versions
of them were a common attack route for years. A .pptx passes where a .ppt
increasingly does not.
Examples
An old training deck for reuse
Four times smaller because .pptx compresses its XML and its media, and easier to email because mail filters no longer flag the extension. Every slide and its formatting came across.
A deck that ran a macro
The plain .pptx container has nowhere to store VBA. If the behavior is needed, .pptm is the format that keeps it; if it is not, this is a clean way to drop it.
Frequently asked questions
Why is the PPTX so much smaller?
Because it is a ZIP archive of XML parts and the old format is an uncompressed binary layout. Slide content compresses extremely well, being mostly repeated structure and text, and embedded images are stored compressed rather than raw. A reduction of three to five times is typical, and nothing is discarded to achieve it.
Will the slides look the same?
Almost always. Slide dimensions, shapes, text formatting, images and slide order all have direct equivalents. Where a difference shows up it is usually a font: a deck laid out around a typeface that is no longer installed will substitute, and substitution changes line breaks. Open the result once and look for text that has overflowed its box.
What happens to macros?
They are not carried, because a plain .pptx cannot contain them. For most old decks this is a benefit rather than a loss: the macro was usually a convenience nobody has used in a decade, and its absence is why mail systems treat the new format as safe. If the deck genuinely depends on VBA, .pptm is the format that keeps it.