SUB Converter

For the most common job, use the dedicated SUB to SRT converter.

How to Convert a SUB File to Any Subtitle Format

1. Upload Your SUB File: Drag and drop your .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.
2. Pick an Output Format: Use the "To format" dropdown to choose your target — SRT is the default, with VTT, ASS, SSA, SBV, SMI, TTML, DFXP, STL, LRC, TXT, and CSV also available. SRT and VTT are the safest picks for the widest player and web support.
3. Check the Frame-Rate Assumption: MicroDVD timing is measured in frames, not seconds, so the conversion to a time-based format like SRT must assume a frame rate. If your subtitles end up early or late after converting, the source video's FPS differs from the assumed rate — see the FAQ below for the fix.
4. Convert and Download: Click "Convert", then download or copy the result. The whole conversion runs entirely in your browser — so it's instant and private: no sign-up and no watermark.

Popular SUB Conversions

• SUB to SRT — the most universal subtitle format, played by virtually every media player and accepted by YouTube and Vimeo
• SUB to VTT — WebVTT, the format HTML5 <track> elements need for browser captions
• SUB to ASS — Advanced SubStation Alpha, for styled and positioned subtitles in Aegisub and fansub workflows
• SUB to SSA — the older SubStation Alpha styling format
• SUB to TXT — strip the timing and keep just the transcript text
• SUB to SMI — SAMI, used by some older Windows Media Player setups
• SUB to STL — Spruce/EBU-style subtitle exchange for broadcast and authoring
• SUB to TTML — Timed Text Markup, used in streaming and captioning pipelines

Why Convert a SUB File?

A .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:

• Universal playback — SRT is the most widely supported subtitle format across desktop players, mobile apps, smart TVs, and streaming uploads. Converting .sub to .srt removes the "subtitles won't load" problem on players that don't read MicroDVD.
• Web and HTML5 captions — browsers don't read MicroDVD or SRT in a <video> element; they need WebVTT. Convert to VTT to caption HTML5 video or to upload to platforms that require it.
• Styling and editing — moving to ASS/SSA unlocks rich positioning, fonts, and karaoke timing in editors like Aegisub, which MicroDVD's handful of inline codes can't express.
• Transcripts — converting to TXT or CSV drops the timing and leaves clean text for transcripts, translation, or indexing.

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.

MicroDVD SUB vs. Common Subtitle Targets

MicroDVD SUB vs. VobSub SUB/IDX — Which Do You Have?

The .sub extension is shared by two unrelated formats. This tool handles the text-based MicroDVD type; here is how to tell them apart before you convert:

If a text editor shows readable lines with curly-brace frame numbers, you have the MicroDVD format this converter reads. If you also have a same-named .idx file and the .sub looks like binary garbage, it's VobSub — a picture-based format that needs OCR software instead.

Frequently Asked Questions

What is the difference between MicroDVD SUB and VobSub SUB/IDX?

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.

Why are my converted subtitles out of sync after converting SUB to SRT?

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.

Will I lose styling when I convert SUB to SRT?

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.

Which output format should I pick for a website video?

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.

Can I convert a SUB file into a plain transcript without timestamps?

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.

How well does the conversion preserve line breaks and timing?

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.

Is my subtitle file kept private?

Yes. The conversion runs entirely in your browser. There is no sign-up and no watermark. Subtitle files are small plain text, so the conversion is near-instant.

Can I batch-convert several SUB files or go the other way?

Yes. You can queue multiple MicroDVD .sub files and download the results together, and the converter runs in reverse — switch the "From format" dropdown to SRT, VTT, ASS, SSA, SBV, SMI, TTML, DFXP, STL, LRC, TXT, or CSV and convert any of those into MicroDVD .sub. Because converting into MicroDVD writes frame-based timing, the result inherits the same frame-rate dependency: the cues are only in sync if the target video runs at the frame rate the file was written against.