Check Subtitles Against the FCC Caption Rules
Or paste subtitle text
Options
The limit is not a number you type in: it is read out of a published document, and the report names that document, quotes the sentence it came from, says whether that sentence is a requirement or guidance, and gives the day we last verified it with a link. Pick the document you are answerable to. They do not agree with each other: Netflix counts characters per second and caps a line at 42 characters, while Ofcom and the BBC count words per minute and, on line length, the BBC caps a line at 37. Three of them state no figures at all — 47 CFR §79.1, WCAG 2.2 SC 1.2.2 and EN 301 549, which requires web pages and non-web documents to satisfy that same criterion. Those three require captions to identify who is speaking and to carry non-speech information, and leave every number to the broadcaster; a page that checks them asks whether the file does it, not whether some number is exceeded. They also do not carry the same weight: a defect that reads as a warning against WCAG reads as an error against EN 301 549, because the standard turns that criterion into a shall. Changing this box changes the limit and the citation together, so a report can never carry one document's number under another document's name. Pages that check something only one of these documents states offer only that one.
Which frame rate the timings are counted in. On the format pages this is what MicroDVD needs, because it stores timing as frame numbers. On the frame rate pages it is the rate the file was timed against — the version the subtitles were made for — and the page's second box takes the rate of the video you are going to use them with. 23.976, 24, 25, 29.97, 30, 50, 59.94 and 60 are the common ones. Getting it wrong shifts the whole timeline, and on the frame rate pages it shifts it by a ratio rather than by a fixed amount.
47 CFR §79.1 is where the FCC states what closed captions on television in the United States have to be, and paragraph (j)(2) sets out four qualities: accuracy, synchronicity, completeness and placement. This page runs every subtitle check it has against that section, and the result is unusual enough to be worth stating before you run it. Four of the five sections come back saying that no limit was given, because §79.1 states no figures at all — no reading rate, no line length, no minimum or maximum duration. The one section that does carry a finding is the one about identifying speakers, because that is the one thing in the section a subtitle file can be measured against. The file is read in your browser, never uploaded, and is not changed.
So this is the honest page of the four. Any subtitle tool can be made to print a table of numbers against the FCC's name; getting a number to print means borrowing it from a style guide the rules do not reference. What this report gives you instead is the state of the section: which of its requirements can be checked in a text file at all, which cannot, and why. Of the four qualities, synchronicity is a statement about timing and can be measured; accuracy means the captions match what was said, which needs the original dialogue to compare against; completeness means nothing was left out, which needs the audio; and placement is about where the caption sits on the screen, which a subtitle file does not record. Four of the five sections of this report are the second, third and fourth of those arriving in the only form they can.
The section also asks for non-speech information — music, sound effects, audience reaction. That half of the same sentence has no check here, and rather than quietly drop it, the report prints it under what was not checked, with the sentence it is quoted from.
Examples
A file where two people speak in one cue
Subtitles
1
00:00:01,000 --> 00:00:03,000
JOHN: I told you not to wait up.
2
00:00:04,000 --> 00:00:07,400
- I know what you did last summer, and I am not going to pretend otherwise.
- Then say it out loud, right here, in front of everybody.
3
00:00:09,000 --> 00:00:09,600
Wait.
4
00:00:11,000 --> 00:00:19,200
MARY: Nothing. It does not matter now.
5
00:00:21,000 --> 00:00:23,000
The quick brown fox jumps over the lazy dog every single morning.
What the report finds
Cues read faster than the limit — Not applicable. No limit was given, so there is nothing to compare against
Lines longer than the limit — Not applicable. No limit was given, so there is nothing to compare against
Cues below the minimum duration — Not applicable. No limit was given, so there is nothing to compare against
Cues above the maximum duration — Not applicable. No limit was given, so there is nothing to compare against
Cues with two speakers and no name — 1 found
Severity Cues Start End Measured Clause
Error 2 00:00:04.000 00:00:07.400 2 items 47 CFR §79.1 — Closed captioning of televised video programming — (j)(2)(i) Accuracy: captioning shall provide nonverbal information that is not observable, such as the identity of speakers
What it was checked against
Standard: FCC caption quality rules (47 CFR §79.1)
Where it is stated: (j)(2)(i) Accuracy: captioning shall provide nonverbal information that is not observable, such as the identity of speakers
Stated as: Requirement
Verified: 2026-10-16
Not checked by this page: (j)(2)(i) Accuracy: captioning shall provide nonverbal information that is not observable, such as the existence of music, sound effects, and audience reactionRead the four sections at the top together: they are the answer to "what does §79.1 require of my reading speed", and the answer is that the section does not say. The one table that does have a row has no Limit column, because the sentence it applies states a duty and no figure. The severity reads Error while the Ofcom and Netflix pages read Warning, and that is the document talking too: this is a regulation, where those are guidance their authors wrote for themselves. The last line is the other half of the same sentence — non-speech information — named rather than omitted.
A file that names speakers everywhere
Subtitles
1
00:00:01,000 --> 00:00:03,000
JOHN: I told you not to wait up.
2
00:00:04,000 --> 00:00:07,000
MARY: I know what you did.
JOHN: Then say it out loud.
3
00:00:08,000 --> 00:00:10,000
- And that is the end of it.
What the report finds
Cues with two speakers and no name — Nothing found.
Checked against
Standard: FCC caption quality rules (47 CFR §79.1)
Where it is stated: (j)(2)(i) Accuracy: captioning shall provide nonverbal information that is not observable, such as the identity of speakers
Stated as: RequirementNothing found, and unlike the four sections above it, that is a real result. The middle cue holds two speaker turns and both are named. The third cue starts with a dash and holds one turn, so there is nobody to identify — a dash marks a change of speaker, and a change needs two people. Take the names off the middle cue and this file turns into one finding; that is the pair of fixtures the page's behaviour is pinned to.
A file that never names anyone at all
Subtitles
1
00:00:01,000 --> 00:00:03,000
- I know what you did.
2
00:00:04,000 --> 00:00:06,000
- Then say it out loud.
3
00:00:08,000 --> 00:00:10,000
MUSIC: Slow piano.
What the report finds
Cues with two speakers and no name — Not applicable. This file never names a speaker, so there is no way to tell whether the ones it leaves unnamed should have been namedThis is the limit of the check, stated in the report rather than hidden. The FCC sentence requires captioning to supply information that is not observable, and whether the audience can see who is speaking is a fact about the picture, not about the text file. A file that names speakers somewhere is evidence that identity is not always visible in this material, which is why the convention exists and can be held to. A file with no names anywhere provides no such evidence, so this page says it cannot judge. Note that MUSIC: does not count as a name: that label is non-speech information, which is the requirement listed under what this page did not check.
Frequently asked questions
What does 47 CFR §79.1 actually state about caption quality?
Paragraph (j)(2) sets out four qualities closed captions on television must have: accuracy, synchronicity, completeness and placement. Accuracy is where the sentence about non-verbal information sits — captioning shall provide nonverbal information that is not observable, such as the identity of speakers, the existence of music, sound effects and audience reaction. Synchronicity requires captions to be displayed at a speed that permits them to be read. There is no numeric threshold anywhere in the paragraph: no characters per second, no words per minute, no line length, no minimum or maximum duration.
Why do four of the five sections of the FCC report say no limit was given?
Because §79.1 states no limit for any of them. The section describes qualities rather than thresholds, so there is no figure to compare a measured value against, and the report says so instead of inventing one. A tool that printed a reading speed table under the FCC's name would be applying a figure from a style guide the section does not reference, and the report would look identical to this one apart from being wrong about where the number came from.
Which of the FCC's four caption qualities can a subtitle file be checked for at all?
Synchronicity, which is a statement about the timeline, and the speaker identification sentence inside accuracy, which is a statement about whether the text names people. The other two cannot be reached from a subtitle file. Accuracy means the captions match what was actually said, which needs the dialogue transcript to compare against; completeness means nothing audible was left out, which needs the audio; and placement is about where the caption sits on the screen, which no text format records. That is why this page reports four sections with nothing to measure rather than presenting empty tables as results.
Why is a speaker finding an error on the FCC page and a warning on the WCAG page?
Because the weight comes from the document, not from the check. 47 CFR §79.1 is a regulation and states the requirement with shall, so the report carries it as an error. The sentence WCAG 2.2 applies sits in the Understanding document for Success Criterion 1.2.2, which is informative material published alongside the criterion, and the report carries that as a warning. Both pages measure the same thing in the same file and both are right about their own document; the difference is what you are answerable to.
What is the FCC requirement this page lists as not checked?
The second half of the sentence it does check: captioning shall provide nonverbal information that is not observable, such as the existence of music, sound effects and audience reaction. No page on this site checks whether non-speech sounds were noted, so the report names the sentence under what was not checked rather than leaving the gap unmentioned. A reviewer who reads a report that says nothing about music will assume music was checked; one line removes that assumption.
Does a clean report mean my captions meet 47 CFR §79.1?
No, and the report does not say so. It says how many cues measured the way this page measures them, which sentence each finding cites, and which parts of the section it did not check. The section binds video programming distributors, and a subtitle file on its own is not what it regulates. Two of the four qualities it states — accuracy and completeness, and placement as well — cannot be assessed from a text file at all, so a clean run here is a statement about the parts that can.
What the check looks for
- The report describes a file, not a service. 47 CFR §79.1 binds television video programming distributors in the United States; it is not a statement about a subtitle file, and nothing here concludes that your captions comply. What the report states is how many cues measured the way this page measures them, which sentence each finding cites, and which requirements of the section this page could not check at all — including two of the four qualities the section states, which no text file can answer.
- There is a second reason this page refuses to report a verdict. The section's own four qualities are partly outside any file: accuracy needs the dialogue to compare against, completeness needs the audio, placement needs the picture. A report that printed numbers for reading speed and line length under this heading would be claiming coverage the section does not give it, and the reader would have no way to tell which parts had actually been examined.
References
- FCC 47 CFR §79.1 — Closed captioning of televised video programming. Paragraph (j)(2) states four caption qualities: accuracy, synchronicity, completeness and placement. Paragraph (j)(2)(i) is the sentence this page applies, requiring captioning to provide nonverbal information that is not observable, such as the identity of speakers and the existence of music, sound effects and audience reaction.
- FCC 47 CFR §79.1(j)(2) — the synchronicity requirement, that captions be displayed at a speed that permits them to be read by viewers. This is the sentence a reading speed check would be measured against, and it states no figure; the report prints no speed table for that reason.