Case Converter

Updated September 2026

The four writing cases

Where AP and Chicago actually differ

They agree far more than they disagree. The gap is prepositions of four letters or more:

Both guides capitalize the last word no matter what, which is why What Are You Waiting For keeps its capital F. Both also capitalize every verb, including short ones: Is, Are and Be are always capitalized in a title, which catches people out because they look like small words.

Why sentence case is winning

Sentence case has quietly taken over most digital writing. Google, Apple and Microsoft all use it for interface text, and several major newspapers switched their headlines to it. Three reasons: it reads faster because capitals are visual speed bumps; it avoids the AP-versus-Chicago argument entirely; and it handles product names gracefully, since a name that is genuinely capitalized stays capitalized while everything else does not.

Rescuing text typed in the wrong case

The classic emergency is a paragraph typed with Caps Lock on. The fix is two clicks, in this order:

1. lowercase — wipes the shouting
2. Sentence case — restores the capital after every period, question mark and exclamation

What no converter can restore is proper nouns. Names, places and brands come back lowercase and have to be fixed by hand, because no tool can tell whether "may" is a month or a verb. Undo is there if a conversion goes somewhere you did not intend.

Everything else is preserved exactly: line breaks, spacing, numbers and punctuation all stay where they were. Only the letters change.

Why ALL CAPS is a real accessibility problem

Setting text in capitals is not just a stylistic choice that reads as shouting. It measurably hurts some readers, and the reasons are worth knowing before you uppercase a paragraph.

It removes the shape of words. Fluent readers do not decode letter by letter; they recognise words partly by their outline, the pattern of ascenders and descenders that letters like l, h, g and p create. Capitals flatten every word into an identical rectangle, so that shortcut disappears and reading slows down. The effect is small on a three-word button and substantial on a paragraph.

Screen readers sometimes spell it out. A word in capitals can be interpreted as an acronym and read letter by letter. "SALE" may be announced as "S-A-L-E". Behaviour varies by screen reader and by how the text was written, which is exactly the problem: you cannot predict it.

It compounds existing difficulties. Readers with dyslexia and readers with low vision both rely more heavily on word shape, so the cost of removing it is not evenly distributed.

The practical rule: use capitals for short labels, buttons and acronyms, never for sentences or paragraphs. If you want the visual weight of capitals in a heading, apply it with CSS text-transform: uppercase rather than typing it — the underlying text stays in sentence case, so screen readers and search engines receive the readable version while sighted users see the styled one. That is why this site's own headings look like capitals in the markup but are not.

The developer cases

Programming languages each settled on a convention, and mixing them is how you get code review comments. The Code buttons above convert between all five, and they read the incoming text intelligently — paste boatLoanCalculator and click snake_case and you get boat_loan_calculator, because the converter splits on the capitals as well as on spaces.

kebab-case is the one with a hard reason behind it rather than a convention: URLs and CSS class names cannot contain spaces, and hyphens are safer than underscores in a URL because some browsers underline links in a way that hides an underscore completely.

Frequently asked questions