Free online SUB converter. Convert SUB to SRT, VTT, ASS, SSA, TXT and more online — no limits, no watermark.
.sub file or click "Upload .sub". This tool handles the text-based MicroDVD .sub format — plain-text lines with frame-number timing. Bitmap VobSub pairs (.sub plus a matching .idx) are a different, image-based format and are not handled here.<track> elements need for browser captionsA .sub extension is ambiguous, so it helps to know which kind you have. This tool converts the MicroDVD .sub format — a plain-text subtitle format developed by Tiamat Software around 2000. Each line looks like {0}{75}Hello there|How are you?: the two numbers in curly braces are the start and end frame numbers, the pipe is a line break, and inline codes like {y:i} mark italics. Because the timing is counted in frames rather than seconds, a MicroDVD file is tied to the exact frame rate of the video it was made for.
That frame-rate dependency is the single biggest reason people convert away from MicroDVD. SRT (SubRip) and VTT (WebVTT) store timestamps as hours-minutes-seconds-milliseconds, so they are frame-rate independent and play correctly regardless of the video's FPS. Common reasons to convert:
.sub to .srt removes the "subtitles won't load" problem on players that don't read MicroDVD.<video> element; they need WebVTT. Convert to VTT to caption HTML5 video or to upload to platforms that require it.Note the trap: a .sub file paired with an .idx file is VobSub, a bitmap subtitle ripped from a DVD. Those are pictures of text, not text, and turning them into SRT requires OCR — a different process this converter does not perform.
| Format | Timing model | Styling support | Native browser captions | Best for |
|---|---|---|---|---|
| SUB (MicroDVD) | Frame-based (FPS-dependent) | Inline codes (italic, bold, color, position) | No | Legacy DivX/MicroDVD players |
| SRT (SubRip) | Time-based (ms) | Basic (bold/italic/underline tags) | No | Universal playback, uploads |
| VTT (WebVTT) | Time-based (ms) | Cue settings, basic styling, CSS | Yes (HTML5 <track>) |
Web video, browser captions |
| ASS / SSA | Time-based (centiseconds) | Rich (fonts, positioning, karaoke) | No | Styled subtitles, fansubbing |
| TTML / DFXP | Time-based (XML) | Rich (XML styling) | Via JS players | Streaming, broadcast pipelines |
| TXT | None (text only) | None | No | Transcripts, translation source |
They share the .sub extension but are entirely different formats. MicroDVD .sub is plain, editable text with frame-number timing — open it in any text editor and you'll see lines like {0}{75}text. VobSub is a .sub binary file of subtitle images paired with a .idx text index, ripped straight from a DVD. This converter handles the text-based MicroDVD type. VobSub can't be turned into editable SRT text without OCR, because there's no text inside it to read — only pictures of words.
MicroDVD timing is counted in frames, so converting to a time-based format like SRT requires assuming a frame rate. If the assumed FPS doesn't match the video the subtitles were authored for, every cue drifts — a 25 fps file read as 23.976 fps slowly falls behind. The fix is to make sure the .sub matches the video's actual frame rate, or to nudge the timing after converting. SRT and VTT, once created, are frame-rate independent, so the drift only comes from the original MicroDVD assumption.
Some, yes. MicroDVD supports inline codes for italics, bold, color (in BGR order), font, size, and position. SRT keeps only basic bold/italic/underline tags, so colors and positioning are dropped in a SUB-to-SRT conversion. If you need to preserve rich styling, convert to ASS or SSA instead, which were designed for fonts, positioning, and karaoke effects.
Use VTT (WebVTT). Browsers read WebVTT in the HTML5 <video> element's <track> tag, but they do not read MicroDVD or SRT natively, so SUB to VTT is the right path for captioning web video. If you're uploading to YouTube or Vimeo instead of self-hosting, those platforms accept SRT, so SUB to SRT is fine there.
Yes. Choose TXT as the output and the conversion strips the frame-timing and styling codes, leaving just the subtitle text — useful as a transcript, a translation source, or for indexing. CSV is also available if you want the text kept alongside its timing in spreadsheet columns. The dedicated SUB to TXT page covers this directly.
In our testing, a MicroDVD .sub using the pipe character for line breaks (for example {0}{75}line one|line two) converts cleanly to a two-line SRT cue, and the start and end frames map to the expected timestamps as long as the frame rate is correct. The text content, line breaks, and cue order come through intact; what changes is the timing model (frames become milliseconds) and any styling SRT can't represent.
Yes. The conversion runs entirely in your browser — your .sub file is parsed and rewritten on your own device and never uploaded to or stored on our servers. There is no sign-up, no watermark, and your file never leaves your computer. Subtitle files are small plain text, so the conversion is near-instant.