Subtitle & SRT Caption CPS Validator
Audits SRT subtitle line lengths (max 37–42 chars) and reading speed (max 15–20 Characters Per Second / CPS) against BBC & Netflix standards.
1. Subtitle Content & Standards
2. Compliance & Velocity Audit
| # | Timecode & Dur | Subtitle Text | Line Chars | CPS | Verdict |
|---|---|---|---|---|---|
| 1 | 00:01.0 → 00:03.2 2.2s |
Welcome to our in-depth video guide on accessibility and subtitle guidelines. |
36, 41 | 15.2 | Pass |
| 2 | 00:03.5 → 00:04.3 0.8s |
This cue has an excessively long line that exceeds standard forty-two characters by quite a margin! | 96 | 32.8 | Line > 42 • Fast CPS |
About this tool
How to use it
- Select your target broadcast or streaming standard (Netflix, BBC, Social Media vertical video, or TED Talks).
- Paste your SubRip (.srt) or WebVTT (.vtt) file contents into the text editor, or drag-and-drop your subtitle file directly.
- Inspect the automated audit KPI summary to review total cues, flagged violations, peak Characters Per Second (CPS), and maximum line characters.
- Use filter pills (Issues Only, CPS Overruns, Line Overruns) to isolate and fix problematic cues.
- Click 'Copy Audit Report' to export the compliance summary for your video editing quality assurance workflow.
Why it matters
Subtitles with excessive reading speed (high CPS) or lines longer than 37–42 characters cause viewer fatigue, obstruct visual action, and fail compliance with major streaming distributors like Netflix, BBC, and Apple TV+. Pre-flight subtitle validation ensures accessibility and broadcast acceptance.
When to use it
Run caption files through this checker prior to final export in Premiere Pro, DaVinci Resolve, or Final Cut Pro, or before submitting master files to digital distributors.
Good to know
HTML formatting tags (such as <i> or <b>) are automatically stripped from character and CPS calculations to measure true human reading velocity.
Common questions
What is the Netflix standard for subtitle line length and CPS?
Netflix mandates a maximum of 42 characters per line and a maximum reading speed of 17 Characters Per Second (CPS) for adult programming (and 13 to 15 CPS for children's content).
What does Characters Per Second (CPS) measure?
CPS measures reading velocity by dividing the total character count of a subtitle cue by its duration in seconds. A higher CPS means viewers have less time to read the text while watching the video.
How many lines of text should appear in a single subtitle cue?
Industry standards across BBC, Netflix, and SMPTE specify a maximum of 2 lines per subtitle cue to avoid obscuring the lower third of the video frame.
Is my video transcript uploaded to any external server?
No. All parsing and timing math runs entirely in your local browser memory via vanilla JavaScript. Zero subtitle text or video scripts are ever transmitted off your device.