Subtitle converter

Drop subtitles in any common format and download them in another: SRT, WebVTT, SCC closed captions, EBU STL or IMSC TTML for Netflix. On the way you can shift or stretch the timing, convert between 23.976, 24, 25 and 29.97 fps, merge, split and de-overlap subtitles, and check them against Netflix reading-speed rules. Captions inside a Final Cut Pro or Premiere Pro timeline export too.

Free, no limits
No upload
SCC, STL and TTML

Drop subtitle files hereSRT, VTT, SCC, EBU STL, TTML, or a Final Cut or Premiere timelineChoose subtitlesConverted in your browser. Nothing is uploaded.

Output format

Timing

Sync by two subtitles

Type where the first and last spoken lines should start; everything in between stretches to fit. Use it when the drift has no known frame rate.

Shift by (seconds)

Positive delays the subtitles, negative shows them earlier. Example: -1.5

Frame rate change

For a video sped up or slowed down to another frame rate, or subtitles timed at the wrong rate.

Clean up

Merge flashes

Joins a subtitle shorter than 5/6 of a second with the next one when both fit on two lines.

Split long subtitles

Rewraps lines over 42 characters and splits anything over two lines into several subtitles, timed by length.

Fix overlaps

Joins repeated lines and ends each subtitle 2 frames before the next one starts.

Check

Delivery guidelines

Flags reading speed, line length, line count, duration and gaps. Clean up uses the same limits.

Reference

Subtitle formats

Subtitle formats
Format	Used for	Timing	Kept here
SRT (.srt)	Editing apps, YouTube, TVs	Milliseconds	Text, italics
WebVTT (.vtt)	Web players, HTML5 video	Milliseconds	Text, italics
SCC (.scc)	US broadcast, Premiere Pro, DVD (CEA-608)	29.97 fps timecode	Text, italics, 4 lines of 32
EBU STL (.stl)	European broadcast (Teletext)	25 or 30 fps timecode	Text, italics
TTML / IMSC (.ttml, .dfxp, .itt)	Netflix, streaming, iTunes	Frames or ticks	Text, italics

Colors, positions and fonts differ between formats and are not carried over; text and italics are.

FAQ

Frequently asked questions

Something else, or a file that will not convert? Write to conform@niamori.ai.

Which subtitle format should I deliver?

Ask the platform, but as a rule: YouTube, social media and editing apps take SRT; web players take WebVTT; US broadcasters ask for SCC closed captions; European broadcasters often want EBU STL; Netflix and most streaming services want IMSC 1.1 TTML.

How do I fix subtitles that drift out of sync?

If the drift comes from a frame rate change, such as 23.976 fps film played at 25 fps, pick that change under Frame rate change. If you do not know the cause, turn on Sync by two subtitles and type where an early and a late line should start; everything in between stretches to fit.

What does the Netflix check look at?

Reading speed (20 characters per second for adult English programs, 17 for children), at most 42 characters per line and two lines, each subtitle on screen from 5/6 of a second to 7 seconds, and at least two frames between subtitles. Each subtitle that breaks a rule is listed with the actual numbers.

Can I get the captions out of my Final Cut Pro or Premiere timeline?

Yes. Drop the FCPXML (or .fcpxmld zipped) from Final Cut Pro and each caption language becomes its own file. From Premiere Pro, export the sequence as Final Cut Pro XML: text graphics and text titles are read as subtitles.

Are my subtitles uploaded?

No. Files are read and converted in your browser and never leave your computer.