How to Convert SRT to TTML for Netflix & Streaming | AllSubConverter
SRT is the subtitle format you find almost everywhere, but professional streaming platforms such as Netflix, Apple TV, and Amazon Prime Video deliver captions as TTML. If you need to submit subtitles to a streaming service, a broadcaster, or an IMSC-compliant workflow, converting SRT to TTML is usually the first step. This guide explains why TTML is required, what changes during conversion, and how to convert SRT to TTML in seconds.
Why Streaming Platforms Use TTML
TTML (Timed Text Markup Language) is an XML-based subtitle format standardized by the W3C and SMPTE. Unlike SRT, which is plain text with no styling, TTML carries structured metadata: timing, regions, fonts, colors, positioning, and language. That structure is what lets a single subtitle file render consistently across a smart TV, a phone, and a set-top box.
Netflix, Apple, and the broadcast industry standardized on TTML because they need more than plain text. They need to control where captions appear on screen, how they look, and whether they meet accessibility regulations such as FCC closed-captioning rules. The IMSC (Internet Media Subtitles and Captions) profile of TTML is the delivery format most streaming services actually require.
The short version: SRT is great for playback, but TTML is the language of professional subtitle delivery.
What Changes When You Convert SRT to TTML
Converting between these formats is not a simple text swap. The converter does three things for you:
1. Timestamps are rewritten. SRT uses HH:MM:SS,mmm with a comma before the milliseconds. TTML expresses timing as begin and end attributes, either in seconds (1.500s) or clock format (00:00:01.500). Both hold millisecond precision, so no timing detail is lost.
2. The file is wrapped in XML. A TTML file is a valid XML document. Each subtitle becomes a <p> element inside a <body>, with a <head> section for styling and metadata. The sequential numbers SRT uses disappear because TTML identifies cues by their attributes, not by a counter.
3. Plain text gains structure. Line breaks become <br/> tags, and the text is placed inside named elements so a player can apply styling and positioning. Because SRT has no styling to begin with, the converted TTML starts unstyled, which you can then enrich in a subtitle editor.
How to Convert SRT to TTML
The fastest way is to use our free SRT to TTML converter. Paste or upload your SRT file, and the tool produces a valid TTML document with the timing, text, and line breaks preserved. Because both formats support millisecond precision, the converted timing is exact.
If your downstream workflow requires an IMSC or EBU-TT profile, the converted TTML is a clean starting point. You can then open it in a subtitle editor to add regions, styling, and language metadata before delivery.
Frequently Asked Questions
Does converting SRT to TTML lose timing accuracy?
No. Both formats support millisecond precision, so the converted TTML holds the exact start and end times of every cue. No rounding is needed.
Is TTML the same as IMSC?
IMSC is a constrained profile of TTML. Every IMSC file is valid TTML, but not every TTML file meets IMSC stricter rules. Converting SRT to TTML gives you the base structure; IMSC conformance is then a matter of adding the required metadata and staying within the allowed styling.
Can I convert TTML back to SRT?
Yes. Use the TTML to SRT converter to extract plain text and timing from a TTML file. Styling and positioning that SRT cannot represent are dropped, but the text and timing remain accurate.