Case converter

Using the case converter

Every control on the screen, what it changes, and the four things it will refuse to do. The tool opens with both boxes empty and a case already selected, so pasting is the only step between you and a result.

The fifteen cases

They are drawn in two groups, and the split is not cosmetic. Text cases change letters and touch nothing else. Code cases build an identifier, so they keep letters and digits and drop the rest.

The bottom eight rows are the reason the two groups are separated. A code case has to split isn't somewhere, because no identifier can carry an apostrophe, and it splits iPhone into i_phone because the capital in the middle is exactly the boundary it is looking for. Both are correct for a variable name and both are wrong for a sentence, which is why the tool says which one you have asked for before you paste the result somewhere.

Turning all caps back into readable text

This is the job most people arrive with, and lower case is only half of it. It gives you a whisper. Sentence case is the one that gives you prose: it brings everything down and then puts a capital back at the start of each sentence.

Finding where a sentence starts is the whole difficulty, and it is where most converters come apart. Three things start one here.

1. The start of the text

   Always, whatever it begins with.

2. The start of a line

   A pasted bullet list has no full stops in it and every item still wants a capital, so a line break counts.

3. A full stop that is not an abbreviation

   Dr., etc., e.g. and 4 p.m. do not end a sentence. Around 90 abbreviations are recognised, and a single letter followed by a stop is read as an initial.

So dr. smith agreed comes back as Dr. smith agreed rather than Dr. Smith agreed. The surname stays down because nothing in the text says it is a name, and inventing a capital there would be a guess dressed as a rule. A lone i does become I, and j. r. r. tolkien does become J. R. R. tolkien, because both of those are rules rather than guesses.

Choosing a title case style

The Style menu appears only when Title Case is selected, because nothing else reads it. Controls that the chosen case ignores are hidden rather than left sitting there, so the bar above the boxes only ever shows what is actually in play. The three published styles disagree about exactly two things, and both are visible in one sentence.

All three keep articles and coordinating conjunctions down in the middle of a title, and all three capitalise the first and last word whatever it is. Both halves of a hyphenated compound are capitalised, so must-read becomes Must-Read. Which style belongs to which kind of writing is the guide's question rather than this page's.

Keeping acronyms as acronyms

Keep acronyms is on by default and it protects any word carrying a capital anywhere but the front. That single rule covers more than it sounds like it does. It shows beside the boxes only for Sentence case, Title Case and Capitalise Each Word, because those are the only three cases that read it.

The protection switches itself off when your text is entirely capitals, and the tool says so under the boxes. In a shouted sentence NASA and THE are the same shape, so there is nothing left to tell them apart. No converter can do better than that, and one that claims to is guessing.

Converting a list in one pass

Every code case runs line by line. Paste a column of forty field names, press snake_case, and you get forty identifiers back rather than one welded together. Blank lines survive, so whatever grouping the list arrived with is still there.

The splitter reads three kinds of boundary, which means you can convert between naming conventions without cleaning the input up first.

• userFirstName and HTTPServerPort split on the capitals.
• date_of_birth and email-address split on the punctuation.
• User First Name splits on the spaces.

So a list mixing all three converts in one press, and HTTPServerPort becomes http_server_port rather than h_t_t_p_server_port.

The buttons around the boxes

Six controls, and the one worth knowing about is Use as input. It moves the result into the left box so the next case builds on it, which is how you run two passes without a trip through the clipboard.

Keyboard

One shortcut, plus the arrow keys. The case picker is a real radio group, so a browser moves between the fifteen cases for you rather than the page reimplementing it.

What the case converter will not do

Four honest limits, and all four are limits of the problem rather than of this page.

• It cannot recover an acronym from shouted text. Paste THE NASA REPORT and Title Case gives The Nasa Report. The information needed to do better is not in the string.
• It does not know your surnames. Sentence case leaves smith down, because a converter that capitalises a random word because it might be a name will capitalise the wrong one eventually.
• Dialogue confuses it. "stop!" he said comes back as "Stop!" He said. Once the case is stripped, that is genuinely indistinguishable from a new sentence starting after a closing quote.
• It has no Turkish dotless i. Case mapping here is the locale-independent Unicode default, so i uppercases to I rather than to İ. German ß does become SS, which is the same default and is correct.

What this one does that the others do not

The converters ranking for this job are not short of buttons. What they are short of is care about the characters that are not letters. I pasted the same two sentences into all seven on 29 August 2026 and wrote down what came back. The method and the full outputs are in the guide; this is the summary.

Three of them turn we met at 4 p.m. and left into we met at 4 p.M. And left, which is what happens when a tool splits sentences on "full stop, space" with no list of abbreviations behind it. Four of them turn NASA into Nasa.

The second row is the one worth reading twice. titlecaseconverter.com is better at title case than this tool is: eight named style guides against three, an explanation for every decision, and a proper-noun dictionary that capitalises a surname where this one leaves it alone. If a style guide is the whole of your problem, use it. This page is for the other fourteen cases, and for having them all in one picker rather than one per page.

Where the text goes

Nowhere. The conversion is a few passes over a string and your browser can already do all of them, so there is no upload, no queue and no server log with your headline in it.

Your last ten runs stay in this browser, so a reload does not lose them, and Clear on the Recent rail removes them. Nothing is uploaded either way.