PPT to PPTX is a transcript, not the slides
People search this to turn a PowerPoint 97-2003 .ppt file into a modern PPTX.
A real old .ppt file cannot be converted in the browser. The tool stops and tells you to open it in PowerPoint and Save As PPTX. If the upload is already a PPTX, the page only re-saves those same bytes.
Animations and masters
Do not rely on this page for a legacy deck. Themes, animations, and video are not rebuilt here because the old format is not read at all.
When PPT to PPTX is the right page
PPT to PPTX sits on this site because PPT and PPTX are not interchangeable, even when they look similar in a file list. People search this to turn a PowerPoint 97-2003 .ppt file into a modern PPTX. People search for PPT when an old machine or a course portal names that extension. Decks are shared as PPTX when the other person will present, and as PDF when they only need to read.
A real old .ppt file cannot be converted in the browser. The tool stops and tells you to open it in PowerPoint and Save As PPTX. If the upload is already a PPTX, the page only re-saves those same bytes.
What you give up by leaving PPT
PPT is the legacy PowerPoint format. Browsers cannot reliably write a true old .ppt file. A real PowerPoint 97 binary is rejected here. Open it in PowerPoint and Save As PPTX.
Keep the file that opens on a computer with PowerPoint.
What you gain, and do not gain, with PPTX
The download has to be PPTX, because that is the format the next step named. Decks are shared as PPTX when the other person will present, and as PDF when they only need to read. Slide text can be pulled out for a handout or a transcript.
If the slides themselves are the deliverable, export from PowerPoint or LibreOffice.
A test that matches the real file
Start from the question the other software asked. If it asked for PPTX, PPT to PPTX is the matching page. If it asked for something else, switch tools instead of hoping a similar extension will pass. People search this to turn a PowerPoint 97-2003 .ppt file into a modern PPTX. A real old .ppt file cannot be converted in the browser. The tool stops and tells you to open it in PowerPoint and Save As PPTX. If the upload is already a PPTX, the page only re-saves those same bytes. The limit is the part people skip, and it is the part that decides whether the download is usable. Do not rely on this page for a legacy deck. Themes, animations, and video are not rebuilt here because the old format is not read at all. The file stays in your browser and is not uploaded. The limit is 100 MB. Keep the original until the download has been opened in the program that will use it. Check three things in the download: it opens, the PPT material you cared about is still there, and the file size or the layout is what the form described. A new extension alone is not those three things. If a portal, a teacher, or a client rejects the file, send them the original PPT as well when you are allowed to. PPT to PPTX is a convenience copy. It is not a new master. Slides are a design. PPT to PPTX can take the words off them or move a file a browser understands. It does not copy animations, masters, or embedded video. When the deck itself is what you will present, export from PowerPoint or LibreOffice. Use this page for a handout or a format a browser can actually write.
Here is the decision for PPT to PPTX. You start with PPT and you stop when a real program accepts PPTX. A PPTX can sometimes be re-saved if it is already the modern file with the wrong expectation. Themes, animations, masters, and embedded video are not cloned by a browser tool. If those two sentences describe a tradeoff you do not want, do not convert. Renaming the extension by hand will not do this job. Running the tool twice on its own output will not do it either.
Do not rely on this page for a legacy deck. Themes, animations, and video are not rebuilt here because the old format is not read at all.
A related step, if you still need one, is PPTX to PPT.
Other jobs start from the homepage, where each tool is named for the conversion it actually does.