Last updated: September 26, 2026

Subtitle Format Converter Guide

Different platforms demand different subtitle formats: editors want SRT, web players want VTT, stylized projects want ASS. Converting between them is mostly mechanical — this guide shows the manual method for each direction, what survives conversion, and when to use a tool instead.

Before converting: keep a master copy

Always keep your original file untouched and convert a copy. Conversions are lossy in one direction (styling in ASS does not survive a trip to SRT), so the master lets you re-convert cleanly later. If your subtitles came from SubEasy, your downloaded SRT is already an ideal master: plain text, precise timestamps, no styling to lose.

SRT to VTT (for web video)

This is the easiest conversion in subtitling. Two changes:

1. Add WEBVTT as the very first line of the file, followed by a blank line.
2. Replace every comma in timestamps with a period: 00:00:03,500 becomes 00:00:03.500.

Any text editor with find-and-replace handles step two in seconds. You can also drop the numeric sequence counters — VTT does not require them — but leaving them in is harmless.

VTT to SRT (for editors)

Reverse the process: delete the WEBVTT header line, swap periods back to commas in timestamps, and make sure cues are numbered sequentially starting from 1. If the VTT used positioning settings (like align:start position:0%) or styling tags, strip those — SRT has nowhere to put them.

ASS to SRT (strip styling)

ASS files contain a [V4+ Styles] section and dialogue lines like Dialogue: 0,0:00:03.50,0:00:06.20,Default,,0,0,0,,Hello world. To get SRT: keep only Dialogue: lines, extract the text after the last comma, convert the timestamps to HH:MM:SS,mmm format, and renumber. Because ASS timestamps use centiseconds, pad the final digit (0:00:03.50 → 00:00:03,500). This is tedious by hand for long files — use a converter tool or a script for anything over a few dozen lines.

SRT to ASS (add styling)

Going the other way, you wrap each SRT cue in ASS dialogue syntax and define your styles (font, size, color, outline, position) once in the header. Fansub editors like Aegisub do this visually: import the SRT, design the style, export ASS. Do this only when you actually need styled output — an SRT with editor-side styling is simpler for most projects.

What survives conversion?

Manual vs tool conversion

Convert by hand when the file is short and the direction is simple (SRT↔VTT). Reach for a tool — Subtitle Edit, Aegisub, or an online converter — for ASS files, batch jobs, or files with hundreds of cues. One caution with online converters: you are uploading your subtitle text to a third-party server, so avoid them for unreleased or confidential content. For the transcription step itself, SubEasy keeps everything in your browser, so there is nothing to leak in the first place.

Quick checklist

• Keep the original as your master; convert copies.
• After converting, open the result in a player (VLC plays all three) and spot-check the first, middle, and last cues.
• Watch for encoding issues: subtitle files should be UTF-8, especially for non-English text.
• File extension must match content — a VTT file saved as .srt will confuse editors.