How is reading time calculated?

Reading time uses an average adult reading speed of 180 words per minute, a common figure for on-screen reading. Total words are divided by 180 and shown as minutes and seconds. Captions are heard faster than read, so this is a guide for the transcript text itself.

Why flag lines over 42 characters?

Broadcast and platform caption guidelines (BBC, Netflix and others) recommend a maximum of around 42 characters per line so the text fits on screen and is readable at a glance. Lines longer than that often get truncated or wrap awkwardly.

What is reading speed in characters per second?

For timed cues, the tool divides each cue's character count by its on-screen duration. Above roughly 17 characters per second for children or 20-32 for adults, viewers cannot comfortably read along, so fast cues are flagged.

Which formats are supported?

SRT (with numeric counters and comma decimal timestamps), WebVTT (with the WEBVTT header and dot decimal timestamps), and plain text. The parser strips timestamps, cue numbers, and VTT tags before counting words.

Does my transcript get uploaded?

No. Parsing, counting, and timing analysis all happen in your browser, and the transcript never leaves your device.

Caption & Transcript Word-Count & Reading-Time

The Caption & Transcript Word-Count & Reading-Time tool turns a raw caption file or transcript into the numbers caption editors actually need: how many words, how long it takes to read, and which cues are too dense or too long to read comfortably on screen.

How it works

The tool first detects the format:

WebVTT — begins with the WEBVTT header; timestamps use a dot decimal (00:00:01.000).
SRT — numeric cue counters and comma decimal timestamps (00:00:01,000).
Plain text — anything else.

It strips cue numbers, timestamp lines, and inline VTT tags, then counts words (runs of non-whitespace) and characters. Reading time is words ÷ 180 wpm. For timed formats it parses each cue’s start/end into seconds and computes:

Words per cue and the average across all cues.
Characters per second = cue characters ÷ cue duration. Cues above ~32 cps are flagged as too fast.
Line length — any line longer than 42 characters is flagged against the broadcast standard.

Example

A VTT cue:

00:00:01.000 --> 00:00:02.000
This single line is far too long to fit on a caption safely.

The line is 60 characters (over 42) and runs at 60 characters in 1 second (60 cps, well over 32), so it is flagged twice — split it across two cues and shorten the lines.

Tips

Keep cues to two lines of at most 42 characters each, and aim for a reading speed your audience can follow.
Reading time at 180 wpm is for the transcript as prose; broadcast captions are timed independently to the audio.
Use the per-cue flags to find exactly where to re-break or re-time before exporting.