Smart Line Break Optimizer & Text Balancer
Fast. Private. Perfect.
Intelligently split subtitle lines at natural grammar pauses and balance two-line lengths for enhanced readability.
Drag & drop your subtitle file here
or click to browse
SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI, TXT, JSON
How It Works
Upload your subtitle file. All major formats are supported.
Set your target characters-per-line limit (default 42, matching common broadcast standards).
The balancer scans each cue and finds the optimal break point near the visual center.
Grammar rules filter out bad breaks (no line ending with a preposition or article).
Download the balanced subtitles with clean, professional line wrapping.
Why Choose AllSubConverter?
Your Privacy Matters
Everything runs in your browser. Your files are never uploaded.
Lightning Fast
Optimized processing engine converts files in seconds.
Free & Local
Each file can be up to 50 MB. Batches can contain up to 200 files or 1 GB total.
Works Everywhere
Works on Windows, Mac, Linux, iOS, Android - any modern browser.
What the Line Balancer Does
Who Needs Line Balancing?
Whisper & Speech-to-Text Cleanup
Auto-generated subtitles from Whisper, YouTube, or Otter often produce long unbroken lines. Balance them instantly.
Fansub & Translation Teams
Manual line wrapping is the most tedious part of subtitling. Automate it with grammar-aware breaking that respects reading flow.
Broadcast & Streaming Delivery
Meet Netflix, BBC, and Disney+ CPL requirements by setting the exact character limit your style guide specifies.
Language Learners
Clean, balanced subtitles are easier to read while learning a new language, improving comprehension.
Frequently Asked Questions
CPL is the maximum number of characters allowed on a single subtitle line. Netflix recommends 42 CPL, BBC uses 37-39, and other broadcasters have their own limits. You can set any CPL value from 10 to 100.
Yes. The balancer detects CJK text and switches to character-based wrapping, which is how CJK subtitles are measured. It also avoids putting punctuation at the start of a line.
Input: SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI. Output preserves the input format where reliable round-tripping is available; otherwise it falls back to SRT.
The balancer avoids breaking a line after leading words like prepositions (of, to, in), articles (a, the), and conjunctions (and, but). It also avoids starting a new line with punctuation. This produces natural, readable breaks.
No. The balancer only adds line breaks (wrapping). It never deletes, rephrases, or modifies any words. Your text content stays exactly the same.
Yes, completely free with no sign-up, no watermarks, and clear file and batch limits. It runs entirely in your browser.