Microsoft's video player takes caption uploads in WebVTT, so an SRT file has to be converted before you can attach it to a Teams recording. The support page for video transcripts and captions names the format in the first words of its upload instructions: "Upload your own WebVTT captions and transcript file by selecting Video settings on the right-hand side of a video's player page."
That one sentence carries both the constraint and the route. Below is the conversion, the upload path verbatim, and the two documented behaviours that surprise people afterwards — a size ceiling written into the error list, and the fact that extra fields in your file are removed rather than rejected.
Before you start
Know where the recording lives. Microsoft's admin documentation splits this by meeting type: "For meetings and events, the recording saves to the organizer's OneDrive, even if the organizer didn't attend the meeting or event. All recording files are saved to the organizer's OneDrive Recordings folder." For channel meetings, "the recording is stored in the SharePoint Teams site documentation library in a folder named Recordings." You need to be able to open that video's player page, because that is where the upload control lives.
Do not go looking for an existing caption file in the folder listing. Microsoft is explicit that "There is no direct access to see or manage the captions and transcript file in the file explorer for OneDrive for Business or SharePoint," and that "Because this file only enhances the video viewing experience, it is viewed and managed only through the video player as described above." Seeing only an .mp4 in the Recordings folder tells you nothing about whether captions exist.
Check why there are no captions in the first place. If the meeting was recorded with transcription switched off, the admin page states the consequence plainly: "If recording is turned on, but transcription is turned off, the recording doesn't have a transcript file stored next to it. Also, when viewing the recording playback in Stream, captions can't be turned on." That is exactly the gap a manual upload fills.
Have an SRT in hand. If the captions came out of Teams itself, note that the live transcript page offers two formats and SRT is not among them: "By default, meeting organizers and co-organizers can download it as a .docx or .vtt file." We cover that in Teams transcript downloads: .docx or .vtt. SRT usually arrives from somewhere else — an editor, a captioning vendor, an older workflow.
Step 1: Convert the SRT to WebVTT
Renaming the extension is not a conversion. Microsoft spells out what a conforming file looks like, and the requirements are structural, not cosmetic:
"The first line must read WEBVTT"
"A time marker (beginning time and end times, separated by an "arrow",
-->). Valid formats for specifying time marker includehh:mm:ss.ttt,hhhh:mm:ss.ttt, ormm:ss.ttt. Use two or four digits for hours (hh or hhhh), two digits for minutes (mm), and two digits for seconds (ss). Separate time markers with a colon (:). After ss, include a period (.) and three digits to represent thousandths of a second (ttt)."
"Text that should appear on the video player during a particular segment of time. Limit text to a maximum of three lines to ensure all the words will fit on the screen."
An SRT file satisfies none of the first two on its own: it has no header line, and its timing lines are not written the way that paragraph describes. Microsoft's page documents the WebVTT side only, so treat the conversion as your job rather than something the player will handle quietly.
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
This runs inside your browser tab: the SRT is read from disk, rewritten with the WEBVTT header and period-separated milliseconds, and handed back. Nothing is uploaded to a server, which matters when the captions are a transcript of an internal meeting. The same converter has its own page at SRT to VTT if you would rather bookmark it.
Step 2: Upload from the video's player page
The route is four moves, quoted in full from Microsoft's page:
"Upload your own WebVTT captions and transcript file by selecting Video settings on the right-hand side of a video's player page. Expand the Transcripts and captions section if closed, then select Upload. In the dialog that appears, select the language of the file you're uploading. Viewers will see this language when they turn captions on or off."
Two details worth pausing on. The entry point is Video settings on the video's player page, not anything in the Teams meeting chat and not the OneDrive file list. And the language you pick in that dialog is not metadata for your own benefit — it is the label viewers see in the captions menu, so a mislabelled upload is a mislabelled experience for everyone who opens the recording.
Step 3: Expect the file to come back simpler than it went in
This is the behaviour most people do not see documented until after it bites. Microsoft's note under the upload instructions:
"Additional fields, such as notes, comments, styles, etc., are not supported and will be removed from the file upon upload."
Read the verb. Not rejected, not fails — removed. Your upload succeeds, and the styling, comments and notes are simply no longer there — with no error to tell you so.
Two errors are documented for uploads that genuinely fail:
"Sometimes there may be errors in your WebVTT file. To work properly, your file must conform to the WebVTT format shown above."
"Your file size exceeds the 4MB limit that this feature supports."
4MB is a lot of subtitle text, so hitting it usually means the file contains more than cues — which loops back to the note above.
Common mistakes
- Renaming
.srtto.vtt. The extension changes; the contents do not. The header line and the timing format are both part of what Microsoft says the file "must conform to." - Styling the captions before uploading. Styles and comments are removed on upload. Do that work after the fact, or accept plain cues.
- Copying the video afterwards. Two official pages describe this with different scope, and both are worth knowing. The admin transcription page: "The transcription link remains for the lifetime of the file in most cases, but can be broken if the video file is copied within the same OneDrive or SharePoint site. This action would result in captions not displaying on the copied video file." The storage page puts it more broadly: "Closed captions aren't fully supported if the Teams meeting recording is moved or copied from its original location in OneDrive or SharePoint."
- Expecting captions inside a downloaded MP4. They are not there. Microsoft: "Captions aren't captured in recordings or downloads. However, you can turn them on while viewing a recording in Teams or in the browser on its Microsoft 365 video player page."
- Editing the transcript to fix a few lines. The page warns that "Teams live transcripts edited in this way lose the speaker attribution of who said what during the meeting."
FAQ
Can I upload an SRT file to a Teams recording? The upload feature is described as taking a WebVTT captions and transcript file, so convert the SRT to VTT first. The conversion is mechanical — header line plus a timing rewrite — and the converter above does it locally.
Where exactly is the upload button? Video settings on the right-hand side of the video's player page, then the Transcripts and captions section, then Upload. You will be asked to pick the file's language in the dialog that appears.
Why did my caption upload fail? Microsoft documents two error cases: a file that does not conform to the WebVTT format shown on that page, and "Your file size exceeds the 4MB limit that this feature supports." Note that non-conforming extras like notes and styles do not cause a failure — they are removed.
Why didn't Teams generate captions automatically for a long recording? The same support page gives two different size figures. Under its size-limit section: "The size limit for running automatic transcripts is 1GB and 4 hours." Further down, under supported file size: "Transcript and closed caption generation are only supported for videos less than 4GB in size and less than 4 hours." The duration matches in both places; the size does not. Plan against the more conservative 1GB, and check the official documentation for the current wording.
Do uploaded captions move with the video file? Microsoft states that "If you move the video file to another location, the transcript will be moved with it. If you copy the video file, a copy of the transcript will be made and stored with it as well" — while also warning, on other pages, that copying can break caption display. Treat the original location as the reliable one.
Converting the file is the only part of this that needs a tool, and it should not need an account or an upload. Browse the rest of the Clapr tools, or read more walkthroughs in how-to guides — including what format Teams recordings actually are.
Quotes above are from Microsoft's own support and admin documentation for Teams recording, transcription and captions, checked 16 September 2026. Microsoft revises these pages — verify against the official documentation before relying on a number.
