Free online STL converter. Convert STL to SRT, VTT, ASS, SSA, SUB and more online — no limits, no watermark.
.stl subtitle file or click "Upload .stl". You can also paste the text directly. This is the EBU STL broadcast subtitle format (EBU Tech 3264), not a 3D-printing model.<track> captions on the webThe subtitle .stl handled here is EBU STL, the Subtitling Data Exchange Format defined by the European Broadcasting Union in EBU Tech 3264, first published on 27 February 1991. It is a binary file built for broadcast: a 1024-byte General Subtitle Information (GSI) header followed by fixed 128-byte Text and Timing Information (TTI) blocks, with frame-accurate timecodes. You can spot it by the STL25.01 (25 fps, PAL) or STL30.01 (30 fps) marker a few bytes into the file. European TV broadcasters and professional tools like Subtitle Edit, EZTitles, and Belle Nuit Subtitler still produce it for in-vision and teletext captions.
To be clear, this is not the 3D-printing stereolithography STL — that .stl is a triangular-mesh model for slicers and CAD. They share an extension and nothing else; if you came here for a 3D mesh, this is the wrong tool.
The reasons to convert away from EBU STL are almost always about reach. Because it is binary and broadcast-specific, you cannot open it in a text editor, most consumer video players ignore it, and web pages cannot read it. Converting turns those rigid GSI/TTI blocks into a plain-text cue format that anything can use:
<track> captions in the browser.| Format | Type | Human-readable | Styling support | Best for |
|---|---|---|---|---|
| EBU STL (Tech 3264) | Binary (GSI + TTI blocks) | No | Teletext color/position | Broadcast exchange, teletext |
| SRT (SubRip) | Plain text | Yes | Minimal (basic bold/italic) | Universal playback, editing |
| VTT (WebVTT) | Plain text | Yes | CSS cue styling | HTML5 web captions |
| ASS / SSA | Plain text | Yes | Rich (fonts, position, effects) | Anime fansubs, styled overlays |
| SUB | Plain text | Yes | Minimal | Legacy / DVD-style players |
| TTML / DFXP | XML | Partially | Rich (XML styling) | Streaming, broadcast pipelines |
| TXT | Plain text | Yes | None | Transcripts, scripts |
| CSV | Plain text | Yes | None | Spreadsheets, translation review |
This tool is for the subtitle STL — specifically EBU STL, the European Broadcasting Union's binary captioning exchange format (EBU Tech 3264). It is completely unrelated to the 3D-printing stereolithography STL, which stores a triangular surface mesh for CAD and slicers. The two formats just happen to share the .stl extension; this converter reads subtitle cues and timecodes, not 3D geometry, so a model file uploaded here will not convert.
EBU STL is a binary subtitle file used by European TV broadcasters, made of a 1024-byte GSI information header and a series of 128-byte TTI text-and-timing blocks. Because it is binary, a plain text editor shows gibberish. It opens in professional subtitle software such as Subtitle Edit, EZTitles, and Belle Nuit Subtitler — or you can convert it here to SRT or VTT and open it in almost any player.
Pick SRT if you want the broadest compatibility — VLC, YouTube, Premiere, and most players and editors read it. Pick VTT (WebVTT) if the captions are going on a website, since the HTML5 <video> <track> element requires WebVTT and supports CSS styling that SRT lacks. Both are plain text, so you can hand-edit either afterward.
It depends on the target. EBU STL can carry teletext color, basic styling, and on-screen positioning. SRT and TXT are nearly style-free, so those attributes are flattened to plain timed text. ASS/SSA and TTML/DFXP preserve much more — fonts, positioning, and styling — so if the broadcast captions were heavily styled, those targets keep the most intent. The cue text and timecodes themselves carry over in every format.
Yes. EBU STL stores frame-accurate timecodes tied to the broadcast frame rate, which the GSI header marks as STL25.01 for 25 fps (PAL) or STL30.01 for 30 fps. The converter reads that frame rate from the header and translates each cue's in/out time into the millisecond-based timing that SRT, VTT, and the other text formats use, so the captions land at the same moments.
No. This subtitle converter runs entirely in your browser using JavaScript — your .stl text is parsed and rewritten on your own device and never sent to or stored on our servers. In our testing, a 600-cue 25 fps EBU STL file converted to SRT instantly with no network request, which means even confidential or pre-release captions stay on your machine. There is no sign-up and no watermark.
Convert to CSV or TXT. STL to CSV lays out each cue as a row with its start time, end time, and text, which drops cleanly into a spreadsheet or a CAT tool for side-by-side translation. STL to TXT gives you a clean running transcript with the timings removed, which is better when you just need the script. Once translated, you can convert the result back to SRT or VTT for playback.