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
WEBVTTheader; 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.
Worked 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.
A corrected version:
00:00:01.000 --> 00:00:02.500
This line is short enough
to fit and read comfortably.Two lines of 26 and 28 characters, at 54 characters over 1.5 seconds = 36 cps — still fast but borderline. Adding another 0.5s of display time would bring it to 27 cps, safely within range.
Caption standards: why 42 characters and 17–32 cps?
The 42-character line limit originates from broadcast television captioning standards (BBC, FCC guidelines, Netflix’s partner spec) that ensure captions fit within the safe-title area of a 4:3 or 16:9 frame without wrapping or truncating. The character-per-second reading speed targets come from research into comfortable on-screen reading:
| Audience | Max chars/sec | Notes |
|---|---|---|
| General adult | 17–32 cps | Most broadcast and OTT standards |
| Children under 12 | 11–17 cps | BBC, EBU recommendations |
| Live captions | Up to 35 cps | Lower accuracy expected |
A 17 cps cap is often recommended for programmes targeting older adults or non-native speakers. Netflix’s timed-text spec allows up to 20 cps for English; some UK broadcast specs allow up to 30 for live content. The tool flags anything over 32 cps as a review candidate — the precise threshold depends on your target platform.
Tips for professional caption editing
- Keep cues to two lines of at most 42 characters each. Three-line cues are generally not accepted by broadcast standards.
- A minimum cue duration of 1.0–1.5 seconds prevents captions from flickering past even if the content is short.
- Don’t break semantic units across cue boundaries if you can help it — “we discussed | the budget” is harder to read than keeping “the budget” with what precedes it.
- 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.