YouTube subtitle formats: which file to upload, and how
Upload subtitles to YouTube in the right format: SRT, SBV, VTT or TTML. See what YouTube keeps, what it drops, and how to convert your file for free.
By Syed Peera Saheb · Published
The short answer
YouTube accepts SRT, SBV, WebVTT, TTML, DFXP, SAMI, LRC and several broadcast formats. For most videos, upload a plain SRT file saved as UTF-8; choose WebVTT or TTML only when you need italics or on-screen positions to survive.
The list below comes from YouTube Help as it read in October 2026. YouTube changes its tools from time to time, so check its page if something looks different. If your file is in a format YouTube does not accept, such as ASS, the converter on this site can turn it into SRT or VTT in your browser without uploading it anywhere.
Which subtitle formats does YouTube accept?
YouTube Help sorts its supported files into basic, advanced and broadcast formats. The table shows what YouTube says it keeps from each one, and whether the converter on this site can write that format for you.
Two details are easy to miss. First, YouTube treats .sub as SubViewer, the same family as SBV. The SUB files this site writes are MicroDVD files, which are a different format, so do not upload them to YouTube; use SRT or SBV instead. Second, the .stl YouTube accepts is EBU STL, a binary broadcast format. The STL this site writes is Spruce STL, a text format with the same extension, and YouTube does not list it.
| Format | Extension | What YouTube says it keeps | This site can write it |
|---|---|---|---|
| SubRip | .srt | Text and timing; no markup. Must be plain UTF-8. | Yes |
| SubViewer | .sbv, .sub | Text and timing; no markup. Must be plain UTF-8. | Yes, as .sbv |
| WebVTT | .vtt | Bold, italic, underline and positioning | Yes, without positioning |
| TTML and DFXP | .ttml, .dfxp | Styling and positioning (YouTube calls this a partial implementation) | Yes, with italic, bold and underline only |
| SAMI | .smi, .sami | Bold, italic, underline and font color; no positioning | Yes, with italic, bold and underline |
| LRC | .lrc | No markup; enhanced LRC is supported | Yes, basic LRC |
| MPsub, RealText, Videotron Lambda | .mpsub, .rt, .cap | Varies | No |
| SCC, EBU STL and other broadcast formats | .scc, .stl, .tds, .cin, .asc, .cap | Broadcast styling, color and positioning | No |
The best subtitle format for YouTube
For ordinary captions, SRT is the best choice: every tool can create it, it is easy to check in a text editor, and YouTube handles it reliably. Its only limitation on YouTube is that formatting is ignored, so italic and bold tags will not show.
- SRT: the default for almost every video.
- WebVTT: when italics matter, for example for off-screen voices or song lyrics, or when you need captions placed somewhere other than the bottom.
- TTML: when your subtitles come from a professional workflow that already produces it.
- SBV: mostly for files you downloaded from YouTube and want to put back. It has no advantage over SRT for new files.
What YouTube removes from your subtitles
YouTube shows uploaded captions in its own player style, and viewers can change the font, size and colors in the player settings. So even formats that carry styling do not control everything. According to YouTube Help, SRT and SBV markup is not recognized at all, WebVTT styling is limited to bold, italic and underline, and SAMI does not support positioning.
ASS and SSA files are not on YouTube's list, so their fonts, colors, positions and karaoke effects cannot reach YouTube in any form. Convert them to SRT or VTT first. The converter keeps the words, timings, line breaks and italic, bold and underline, and drops the rest; the guide to ASS and SSA subtitles explains what that means for signs and songs.
How to upload subtitles to YouTube
These are the steps YouTube Help described in October 2026. Menu names can change, so follow YouTube's current wording if it differs.
- Sign in to YouTube Studio and choose Subtitles from the menu on the left.
- Select the video you want to add subtitles to.
- Choose Add language and pick the language of your file, if it is not listed yet.
- Under Subtitles, choose Add, then Upload file.
- Choose With timing for an SRT, SBV, VTT or other timed file, then Continue.
- Choose your file, check a few captions in the preview, and save.
Convert your file to a YouTube format
If your subtitles are in ASS or SSA, open them in the ASS to SRT or ASS to VTT converter and download the result. Lines that were signs or song titles placed around the screen become ordinary captions at the bottom, so look through the preview before you upload.
MicroDVD SUB files count video frames rather than seconds. When you convert one to SRT, the converter uses the frame rate written in the file, or the one you choose if the file does not say, 23.976 frames per second by default. If the converted captions drift steadily away from the speech, try another frame rate, such as 25.
For a whole season or a course with many videos, drop up to 100 files on the converter at once and download them together as a ZIP. Every file is saved as UTF-8, which YouTube requires for SRT and SBV, and nothing is uploaded while you convert.
Download, fix and re-upload YouTube captions
If you own the video, the Subtitles page in YouTube Studio also lets you download an existing caption track. Depending on the track, you may get an SBV, SRT or VTT file. Open it in the matching converter, such as SBV to SRT, if another program needs a different format.
To fix timing, use the subtitle time shifter: move everything earlier or later, change the frame rate, or match two captions. To remove repeated lines from automatic captions or bracketed sound descriptions, use the subtitle cleaner. Keep the same format when you are done, and upload the file again as a new version of that language's track.
Why YouTube rejects a subtitle file or shows it wrong
Most problems come from a handful of causes. Work through this list before trying another format.
- The file is not UTF-8. Accented letters turn into symbols or the upload fails. Open it here, pick the right encoding if the preview looks wrong, and download it again as UTF-8.
- The file was renamed instead of converted. A .vtt file renamed to .srt still has the WEBVTT header and dots in its times. Convert it properly.
- A WebVTT file is missing its WEBVTT first line. Converting it from SRT adds the header.
- Captions overlap, or lines are too long to read. The subtitle checker lists both, along with captions that flash by too quickly.
- The captions drift away from the speech. That is a frame-rate or edit problem; see the guide to subtitles that are out of sync.
- The file is ASS, SSA, Spruce STL or MicroDVD SUB. Convert it to SRT first.
Common questions
Does YouTube accept VTT files? Yes. YouTube Help lists WebVTT and says it keeps bold, italic, underline and positioning.
Can I upload ASS subtitles to YouTube? No. ASS is not on YouTube's list. Convert the file to SRT or VTT, keeping in mind that fonts, colors and positions are lost.
Why did my italics disappear? YouTube ignores markup in SRT and SBV files. Upload a VTT file instead if italics matter.
Is SBV better than SRT? No. YouTube treats both as plain text with no markup. SRT is more widely supported elsewhere, so it is the better choice for new files.
Which text encoding should I use? UTF-8. YouTube Help says SRT and SBV files must be plain UTF-8, and every file this site saves is UTF-8.
Does the converter upload my file? No. It reads and converts the file in your browser, and the result is saved straight from the page.