How to Translate Subtitles (SRT, VTT) with AI, for Free and Offline

Why Translate Subtitles?

Subtitles are one of the cheapest ways to reach a new audience:

a YouTube channel or online course that wants international viewers,
a short film submitted to foreign festivals,
a corporate video for teams in several countries,
a film or series whose subtitles only exist in one language,
language learners who want subtitles in their native language and the original.

Translating a subtitle file by hand is tedious: hundreds of lines, each with its timing to preserve. An AI translator does the bulk of the work in a few minutes.

SRT and VTT in 30 Seconds

The two most common subtitle formats are plain text files:

1
00:00:01,200 --> 00:00:03,800
Hello, and welcome to the course.

2
00:00:04,100 --> 00:00:06,500
Today we'll talk about color.

SRT (SubRip): the most universal, read by VLC, YouTube, video editors and TVs.
VTT (WebVTT): the web standard (HTML5 video players), with optional styling and notes.

Each block contains a number, a start and end time, and the text. When translating, only the text must change — the timings must stay exactly the same.

Translate a Subtitle File in 3 Steps

The subtitle translator uses MarianMT translation models (Helsinki-NLP), running entirely in your browser. Your subtitles are never uploaded — useful for unreleased films or internal videos.

Subtitle Translator

Translate SRT and VTT files with AI, in your browser.

Try it for free

Import your SRT or VTT file.
Choose the language pair: from English to French, Spanish, German, Italian, Portuguese or Dutch, or from one of these languages to English.
Translate and download the file: same format, same timings, translated text.

The first run downloads the model for the language pair (about 110 MB), which takes 10 to 60 seconds depending on your connection. After that, it's cached: a 90-minute film with about 1,000 lines is translated in 1 to 4 minutes on a modern computer — even offline.

Translating between two non-English languages

Each model handles one language pair with English. To go from French to Spanish, translate to English first, then from English to Spanish.

What's Preserved

Timings: unchanged, to the millisecond.
Formatting tags (italics, bold) and line breaks within a subtitle.
Dialogue lines starting with a dash.
For VTT: the header, styles and notes.
The file's encoding issues (old Latin-1 SRT files, Windows line endings) are handled when reading.

How to Get the Best Result

Machine translation is very good on everyday dialogue, but it's not a professional subtitler. A few tips:

Start from clean subtitles: typos and approximate transcriptions are translated as is.
Re-read the result, especially jokes, wordplay, idioms and proper nouns.
Check the length: some languages are 20–30% longer than English (French, Spanish, German). A subtitle that becomes too long is hard to read in time — shorten it.
Respect reading speed: about 15–17 characters per second is a comfortable maximum for viewers.
Have a native speaker proofread for a commercial release.

Adding the Subtitles to Your Video

YouTube: YouTube Studio → Subtitles → Add language → Upload file.
VLC: drag the SRT file onto the playing video, or give it the same name as the video file.
Video editors (Premiere, DaVinci Resolve, CapCut): import the SRT as a caption track.

Need to cut the video first? The video trimmer keeps the passage you want — remember that the subtitle timings then need to be shifted accordingly.

Conclusion

Translating subtitles with AI turns hours of tedious work into a few minutes: the timings are preserved, the formatting is kept, and you only need to proofread. With models that run in your browser, your files stay private and the tool works even offline.