Subtitle Validator
Check overlaps, empty entries, format errors, and CPS against Netflix, BBC & EBU standards
Input Subtitle
Validation Rules
When to Use Subtitle Validator
Streaming Platform Delivery
Netflix, Amazon, and Disney+ all have strict subtitle standards. Run validation before delivery to catch CPS, line length, and overlap violations before submission.
Post-Translation QC
After translating subtitles, character counts and CPS often change. Validate translated files to ensure they still meet the target platform's requirements.
AI Subtitle Audit
AI-generated subtitles frequently have overlaps, empty cues, and timing issues. Run a quick validation pass to identify and fix problems before distribution.
Broadcast Compliance
EBU and BBC standards specify CPS limits, maximum line lengths, and minimum display durations. Validate against EBU/BBC preset before broadcast delivery.
Accessibility Review
High CPS subtitles are inaccessible to viewers with reading difficulties. Use the validator to ensure subtitles are readable for all audiences including those with dyslexia.
Pre-Merge Sanity Check
Before merging or splitting subtitle files, validate each input to ensure no timing conflicts exist that could compound into larger issues in the combined output.
Frequently Asked Questions
What is CPS in subtitle validation?
CPS (Characters Per Second) measures reading speed required to follow a subtitle. It is calculated as text length (including spaces) ÷ display duration in seconds. Netflix limits CPS to 20; EBU/BBC use 17. High CPS means the subtitle is shown too briefly relative to its text length.
What counts as a subtitle overlap?
An overlap occurs when one cue's end time is later than the next cue's start time. For example, Cue 1 ending at 00:00:05,500 and Cue 2 starting at 00:00:05,200 creates a 300ms overlap. Most players will cut off one cue, causing missing text.
What is the Netflix subtitle standard?
Netflix requires: max 20 CPS, max 42 characters/line, max 2 lines/cue, min duration 833ms, max duration 7 seconds, and no overlapping cues. Select the Netflix preset to validate all these rules at once.
What is the difference between Error and Warning?
Errors are structural problems that will cause malfunction: overlapping cues, invalid timestamps, empty entries. Warnings are quality violations that affect readability but won't break playback: CPS over limit, lines too long, too many lines, or unusual durations.
Is my file uploaded to a server?
No. All validation happens entirely in your browser using JavaScript. Your subtitle content is never sent to any server, ensuring complete privacy.
What is the minimum gap check?
Netflix requires a minimum 2-frame gap (≈83ms at 24fps) between consecutive cues. When enabled, this check flags cue pairs whose gap is smaller than the configured threshold. A gap of 0ms means cues are touching but not overlapping — technically valid, but flagged as info.
Which subtitle formats are supported?
SRT and WebVTT are both supported. The tool auto-detects the format and applies appropriate format-specific checks, such as validating the required WEBVTT header for VTT files.
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