Add your SMI file
Drop one or more .smi files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
SMI to SRT
Converting a .smi file to .srt extracts the document's content from its office package into a portable form. Free, private, and validated — the file never leaves your browser.
Private for supported formats — processed in your browser
Runs on your deviceConvert supported files
Drop SMI files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting SAMI captions to SubRip subtitles
Converting a .smi file to .srt extracts the document's content from its office package into a portable form. An .smi file is a SAMI caption document: HTML-like markup in which <SYNC Start=…> elements mark the millisecond at which a caption appears, and the caption runs until the next SYNC. Microsoft designed it as an accessibility format, so a single file can carry several languages selected by CSS class.
A .srt file is a SubRip subtitle document: numbered cues with start and end timestamps and plain caption text. It is the most common caption sidecar for video players, editors, and streaming toolchains that need a simple, widely understood text format. For this route the practical draw is universally understood by media players and editors and human-editable in any text editor — balanced against no standard support for advanced styling, voices, or regions, which is worth knowing before you commit a large batch.
Why convert SMI to SRT?
The practical trigger for this conversion is usually a mismatch: with .smi, never formally standardised, so real-world files vary in structure. Switching to .srt buys you universally understood by media players and editors, which is why it is the better fit for delivering captions alongside MP4 or MKV downloads. Because the conversion runs locally, trying it costs nothing but a few seconds of compute on your own machine.
SMI vs SRT at a glance
| Aspect | SAMI captions (.smi) | SubRip subtitles (.srt) |
|---|---|---|
| Format type | Text-based — characters and structure, so there is no visual quality loss | Text-based — characters and structure, so there is no visual quality loss |
| How it stores data | the document has an HTML shape: <SAMI> wrapping <HEAD> with a <STYLE> block and <BODY> with the SYNC elements | cues are blocks of an index, a timecode arrow line (HH:MM:SS,mmm --> HH:MM:SS,mmm), one or more text lines, and a blank separator |
| Strongest at | captioning legacy Windows Media and Silverlight content | delivering captions alongside MP4 or MKV downloads |
| Weak spot | never formally standardised, so real-world files vary in structure | no standard support for advanced styling, voices, or regions |
Pick SRT as the output
Select .srt in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if SRT is selectable, the route is real and validated.
Convert on your device
Press Convert. The package is unzipped in memory and its XML content parsed locally; nothing is uploaded.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid SRT file. Outputs keep the original filename with the .srt extension.
SMI to SRT questions, answered
Will converting SMI to SRT lose quality?
There is no visual quality to lose — smi is text-oriented and srt is text-oriented, so the question is structural fidelity. Text, ordering, and basic structure are preserved; complex layout, embedded objects, and styling beyond the target's model are simplified.
Is it private to convert SMI files here?
Yes — the .smi file is processed inside your browser tab and never uploaded. The package is unzipped in memory and its XML content parsed locally; nothing is uploaded. Close the tab and the file is gone from memory.
Where will the SRT file work?
VLC, MPC-HC, PotPlayer, Premiere, HandBrake, YouTube, and virtually every desktop player ingest .srt. Browser video elements usually prefer WebVTT, so conversion is common for web delivery.
Will the SRT file be bigger or smaller than my SMI?
It depends on the content: cues are blocks of an index, a timecode arrow line (HH:MM:SS,mmm --> HH:MM:SS,mmm), one or more text lines, and a blank separator. Convert one representative file first and compare before batch-processing a large set.
What happens to the metadata in my SMI file?
In .smi, style-class and title information describes presentation and language selection, not the cues; conversion keeps timing and text. Re-encoding through the browser pipeline does not carry embedded metadata into the output, which doubles as a privacy scrub — check the exported file if you specifically need tags preserved.
Can I convert SRT back to SMI?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .smi → .srt → .smi is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.