Convert Subtitles to lowercase
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Five named rules live behind this one box, and each has a page of its own: UPPERCASE and lowercase rewrite every letter, title case capitalises each word and leaves the small ones (a, the, of) alone, sentence case lowers the line first and then rebuilds the sentence starts, and Capitalise each line changes only the first letter of each line. This page fills the box in with the rule its title names and lists no other, so the file this page produces is the one the page is about.
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.
This page rewrites every subtitle line in lower case. It is the blunt version of the operation: every letter that has a lower-case form is lowered, sentence openings included, and acronyms and brand names go down with them — NASA becomes nasa and iPhone becomes iphone. That is what all-lower-case means, and it is the point of the page rather than a limitation of it, so it is said plainly here rather than discovered later.
You are probably here because something downstream asked for it. A handful of platforms and house styles specify lower-case subtitle text, and a file that has to be handed over that way has to be handed over that way. It is worth knowing what you are trading: text in all lower case is measurably slower to read than mixed case, and the lost capitals are exactly the signal a reader uses to find the start of a sentence and to spot a name. Where you have a choice, keep your subtitles in mixed case.
If you want a file that reads normally rather than one that satisfies a spec, the page next to this one is the one you want. Capitalise the first letter of every line leaves the rest of each line alone; sentence case lowers everything and then rebuilds the sentence openings, which is what to run on a file that arrived in capitals. Both are one click away and neither is a variant of this page — they produce genuinely different files from the same input.
Nothing is uploaded, so a file that must not leave the machine does not leave it: everything is read and written in the browser tab. SRT, WebVTT, ASS, SSA, SBV, SAMI, LRC, MicroDVD, TTML, JSON, TXT and CSV are all read as what they actually contain, and a file that was already in lower case comes back byte for byte.
Examples
An ordinary two-cue file
Input
1
00:00:01,000 --> 00:00:02,000
The Room Is Dark.
2
00:00:03,000 --> 00:00:04,000
She LEFT.
Output
1
00:00:01,000 --> 00:00:02,000
the room is dark.
2
00:00:03,000 --> 00:00:04,000
she left.
Every letter comes down, including the sentence openings — `The` at the start of a line becomes `the` like any other word, because this page has no notion of a sentence. The timecodes, the cue numbers and the punctuation are untouched, and the file still holds the same two cues in the same order.
Acronyms and brand names go down too
Input
1
00:00:01,000 --> 00:00:02,000
NASA and the FBI.
2
00:00:03,000 --> 00:00:04,000
<i>iPhone</i> owners.
Output
1
00:00:01,000 --> 00:00:02,000
nasa and the fbi.
2
00:00:03,000 --> 00:00:04,000
<i>iphone</i> owners.
Worth checking before you run this over a whole series: acronyms and brand names are lowered like everything else, so `NASA` becomes `nasa`. The italic styling does survive, because lower-casing a character never makes the string longer or shorter, so each styled range still covers exactly the words it covered before.
Digits, symbols and music notes
Input
1
00:00:01,000 --> 00:00:02,000
♪♪ And 42 % said No.
2
00:00:03,000 --> 00:00:04,000
So did 007.
Output
1
00:00:01,000 --> 00:00:02,000
♪♪ and 42 % said no.
2
00:00:03,000 --> 00:00:04,000
so did 007.
Only letters have a case. The music notes, the percentage sign and both numbers pass through untouched while the words around them come down, so a file that marks non-speech sound with symbols is not damaged by a case change.
Frequently asked questions
Will lower-casing my subtitles make them harder to read?
Yes, and it is worth saying so before you run it over a whole series. Text without capitals loses the signal readers use to find sentence openings and recognise names, and most accessibility guidance asks for normal mixed case rather than all lower case. This page exists for the case where a platform or a house style demands lower-case text — treat it as a delivery step, not as a way to tidy a file up.
What happens to acronyms and brand names?
They are lowered with everything else: NASA becomes nasa, iPhone becomes iphone. There is no exception list and no way to add one, because a page that guessed which words deserve their capitals would be right most of the time and silently wrong on the rest. If your file is full of acronyms and only a few lines need lowering, find and replace on those lines will do less damage.
Is there a page that lowers a file and then puts the capital letters back where they belong?
Yes — that is sentence case, and it is the page most people actually want when they arrive at this one. It lowers each line and then rebuilds it as sentences, giving a capital to the first word and to every sentence start, which turns a file written in capitals into a normal reading file. It does not restore proper nouns, since nothing in the file records which words those were.
Does the case change affect the timecodes or the cue numbering?
No. The only thing this page touches is the text of each line, so cue start and end times are the file's own to the millisecond, the cue order is unchanged, and on formats that number their cues the numbers are rewritten exactly as they came in. That makes it a safe step to add anywhere in a workflow, including after a timing pass you have already checked.
Can I lower-case only part of a file, such as the dialogue but not the speaker labels?
Not here — the whole file is converted. The practical route for a partial change is find and replace, which can target a word or a phrase anywhere in the file without touching the lines that do not contain it, or splitting the file first and converting one part. A dropped file has nothing in it that says which cues you meant, so a page cannot ask.
How are accented letters and the Turkish dotless i handled?
Accented Latin letters are lowered normally, since the browser's own case rules know about them. Two things can surprise you. The Turkish dotted capital i lowers to two characters rather than one, and where that happens the tags on that line are dropped rather than left pointing at the wrong letters — the count is reported. And the dotless i is matched by the default international rules rather than the Turkish ones, so a file in Turkish may need a hand check afterwards.