SRT to ASS — Convert SRT Subtitles to Advanced SubStation Alpha
Convert SRT subtitle files to ASS format with full styling support. Add fonts, colours, positions, and karaoke effects — all in your browser.
SRT to ASS
Convert SRT subtitles to ASS (Advanced SubStation Alpha) format. Generates a complete ASS script with default styling. Works entirely in your browser.
SRT is the universal subtitle format — every video player, every streaming platform, and every captioning tool reads and writes it. Its strength is its simplicity: a sequence number, a timestamp range, the text, and a blank line. That simplicity is also its limitation: SRT has no concept of style. Every line is rendered in the player’s default font, at the player’s default position, in the player’s default colour. For fansubbers, video editors, and anyone who wants subtitles that look deliberate rather than default, the missing piece is ASS — Advanced SubStation Alpha — the format that Aegisub made the standard for styled subtitling.
The conversion from SRT to ASS is about adding a style layer to timing data that is already correct. The SRT provides the cue timestamps and the spoken text. The tool wraps that data in an ASS script with a configurable style header: font face, size, primary and secondary colours, outline width and colour, shadow depth, alignment anchoring, and margin. The result is an ASS file that plays identically to the source SRT in timing, but renders with the chosen visual style in any libass-based renderer — FFmpeg, VLC, mpv, Jellyfin, Plex. The tool runs entirely in your browser and never sends your subtitle files to a server.
How to use
Paste or drop your SRT file
Drop an .srt file or paste subtitle text. The parser reads timing blocks, cue numbers, and text content. Multi-line subtitle entries are joined into single ASS dialogue events.
Choose a style preset
Pick from built-in presets — default, classic yellow, white outline, or custom. Each preset sets the font face, size, primary colour, outline, shadow, alignment, and margin values.
Download the .ass file
The generated ASS includes a complete [V4+ Styles] section, a [Events] section with formatted dialogue, and a [Script Info] header. Drop it directly into Aegisub, FFmpeg, or VLC.
Frequently asked
What does ASS support that SRT cannot express?
SRT carries only timing and plain text. ASS adds per-line font selection, colour, outline width and colour, shadow, alignment (top/middle/bottom + left/center/right = 9 positions), scaling, spacing, rotation, and drawing commands for karaoke and typesetting.
Can I adjust the style after conversion?
Yes — the generated ASS file has a clean [V4+ Styles] section with the preset's values. Open it in Aegisub or any text editor, change the style parameters, and every line referencing that style updates together.
Does it preserve HTML tags from SRT?
Bold (`<b>`), italic (`<i>`), and underline (`<u>`) tags are converted to ASS override codes (`{\b1}`, `{\i1}`, `{\u1}`). Colour tags (`<font color="#rrggbb">`) become ASS colour overrides. Unsupported HTML tags are silently stripped.
Why ASS instead of SSA?
ASS (Advanced SubStation Alpha) is the successor to SSA (SubStation Alpha) and adds more styling features — shearing, rotation around X/Y/Z axes, drawing commands, and per-style encoding declaration. Every modern subtitle renderer supports ASS natively.
Limitations
- No typesetting detectionThe converter applies a uniform style to every line. Complex typesetting — per-syllable timing, sign translations positioned over the original text — requires manual work in Aegisub after conversion.
- No karaoke generationThe converter converts text and timing, not syllable-level karaoke timing. For karaoke effects, generate the base ASS with this tool and add karaoke timing in Aegisub.
- Format-specific features not preservedSRT's positional tags (X1/Y1/X2/Y2 coordinates after the arrow) are mapped to ASS's \pos override, but the mapping is approximate since ASS coordinates are relative to the video resolution declared in the script header.
Platform notes
- macOS
- Aegisub runs on macOS via Homebrew (`brew install aegisub`). Open the generated .ass file to preview styles before embedding with FFmpeg.
- Windows
- Aegisub on Windows is the standard ASS editor. The generated file opens directly — double-click the .ass in Explorer after setting Aegisub as the default handler.
- Linux
- FFmpeg on Linux burns ASS subtitles with `ffmpeg -i video.mp4 -vf "ass=subtitles.ass" output.mp4`. The libass library handles all ASS features including drawing commands.
- Web
- Jellyfin and Plex both render ASS subtitles natively through libass. Upload the .ass alongside your media file for styled subtitles without transcoding.