# Subtitle Reading Speed & Localization Auditor

Audit SRT, WebVTT, and ASS subtitles for CPS, duration, line length, overlaps, and translation expansion risk.

> Canonical page: https://elysiatools.com/en/tools/subtitle-reading-speed-localization-auditor

- **Category:** Media

- **Keywords:** subtitle CPS, subtitle QA, localization, SRT audit, WebVTT audit

## Overview

Reports per-cue characters per second, line limits, line count, and a projected reading-speed risk when translated text expands. Netflix-style presets are practical QA profiles; the EBU preset is an EBU-oriented workflow profile, not a certification.

## Inputs

- **Subtitle text** (textarea): Paste SRT, WebVTT, or ASS text
- **Subtitle file** (file)
- **Input format** (select)
- **Preset** (select)
- **Maximum CPS** (number)
- **Maximum line length** (number)
- **Maximum lines** (number)
- **Translation expansion risk (%)** (number)

## When to use

- Before delivering subtitle files to streaming platforms to ensure compliance with strict CPS and line length limits.
- During the localization prep phase to identify fast-paced dialogue cues that might exceed reading speed limits when translated into longer target languages.
- When quality-checking SRT, WebVTT, or ASS files for overlapping timestamps, excessive line counts, or text truncation issues.

## How it works

- Paste your subtitle text directly into the input area or upload an SRT, WebVTT, or ASS file.
- Select a compliance preset, such as Netflix or EBU, or customize your limits for maximum CPS, line length, line count, and translation expansion percentage.
- Run the audit to generate a detailed report highlighting specific cues that violate your parameters or pose a high risk during localization.

## Use cases

- Pre-flight QA testing of SRT files against Netflix-style reading speed constraints before final delivery.
- Estimating localization bottlenecks by identifying cues that will become unreadable if the target language expands by 20%.
- Cleaning up WebVTT files by flagging lines that exceed 42 characters or contain more than two lines of text.

## Frequently asked questions

### What subtitle formats does the auditor support?

The tool supports SRT, WebVTT, and ASS subtitle formats, which can be auto-detected or manually selected.

### What is CPS and why does it matter?

CPS stands for Characters Per Second. It measures reading speed to ensure viewers have enough time to read each subtitle cue before it disappears.

### How does the translation expansion risk calculation work?

It simulates how much the text length might grow when translated (e.g., by 20%) and flags cues that would exceed CPS limits after expansion.

### Are the Netflix and EBU presets official certifications?

No, they are practical QA profiles modeled after industry guidelines to help you align with their workflows, not official certifications.

### Can I set custom limits for my subtitle audit?

Yes, you can select the 'Custom' preset to manually define your own maximum CPS, line length, line count, and expansion risk percentage.

## Related tools

- [Audio Read-Along Cue Generator](https://elysiatools.com/en/tools/audio-read-along-cue-generator): Generate sentence or word-level timestamp cues from a narration audio and its script, for karaoke-style reading and language learning.
- [Stream Probe Report](https://elysiatools.com/en/tools/stream-probe-report): Readable stream and codec report for media files.
- [Video Subtitle Translator](https://elysiatools.com/en/tools/video-subtitle-translator): Extract or import subtitles, translate them with AI, and export clean SRT or ASS files while preserving timing and subtitle structure
- [PDF Logical Structure Tree WCAG Role Mapping Validator](https://elysiatools.com/en/tools/pdf-logical-structure-tree-validator): Audit a tagged PDF's logical structure tree against PDF/UA-1 (ISO 14289-1) semantics: RoleMap termination, H1-H6 heading hierarchy, Alt text on Figure/Formula, RFC 3066 language tags, illegal nesting, and structure-vs-content MCID reading order — each finding labeled with its Matterhorn Protocol checkpoint.
- [Audio Caption Sync Checker](https://elysiatools.com/en/tools/audio-caption-sync-checker): Compare SRT or WebVTT cue timing with likely speech activity and flag timing drift.
- [Video Subtitle Add](https://elysiatools.com/en/tools/video-subtitle-add): Add hardcoded subtitles to videos using SRT, ASS, or VTT subtitle files with customizable font styling
- [Video Subtitle Embed](https://elysiatools.com/en/tools/video-subtitle-embed): Embed subtitle files as soft subtitles in videos (switchable subtitle tracks, not burned into video)
- [Video Subtitle Extract](https://elysiatools.com/en/tools/video-subtitle-extract): Extract subtitle tracks from video files in their original format (no conversion)

## Samples

- [SRT Subtitle Samples](https://elysiatools.com/en/samples/srt-samples): Sample SRT subtitle files from simple to complex for testing import, translation, conversion, and timing-preservation workflows
- [ASS Subtitle Samples](https://elysiatools.com/en/samples/ass-samples): Sample ASS subtitle files from simple to complex for style-aware subtitle parsing, translation, conversion, and localization QA
- [VTT Subtitle Samples](https://elysiatools.com/en/samples/vtt-samples): Sample WebVTT subtitle files from simple to complex for subtitle previews, parser testing, conversion, and note handling
- [Copyright-Free MP3 Audio Samples](https://elysiatools.com/en/samples/mp3-samples): Collection of royalty-free audio samples for testing and development purposes including nature sounds, meditation music, and ambient audio