Choosing the Right Text Case
Paste text, pick a case style, and the converted result appears instantly. Eight styles are supported, covering both writing conventions and the naming conventions used in code and URLs.
Case is not just a formatting preference. Different contexts have genuine conventions, and using the wrong one ranges from looking careless to actually breaking things — a URL in mixed case can create duplicate pages on a case-sensitive server.
The eight styles and where each belongs
- UPPERCASE — acronyms and short labels. Avoid for headings or body text; it reads as shouting and is measurably slower to read.
- lowercase — normalising data before comparison, and some minimalist design systems.
- Sentence case — the default for headings and subheadings in most modern style guides, including UK publishing.
- Title Case — headlines and titles in US publishing conventions, with minor words left lowercase.
- camelCase — JavaScript variables and function names.
- PascalCase — class names and React component names.
- snake_case — Python variables, database columns and some file naming.
- kebab-case — URL slugs, CSS class names and HTML attributes.
Sentence case versus Title Case for headings
Both are correct; they belong to different conventions. US publishing traditionally uses Title Case for headlines, capitalising major words and leaving articles, short prepositions and conjunctions lowercase. UK publishing and most modern web style guides use sentence case, capitalising only the first word and proper nouns.
Sentence case has gained ground online for practical reasons. It is easier to apply consistently — Title Case rules about which minor words to lowercase are genuinely fiddly and people get them wrong — and it reads slightly faster because capitalisation patterns match ordinary prose.
The thing that matters more than the choice is consistency. Mixed conventions across a site's headings look unconsidered. Pick one, apply it everywhere, and use the Title Case Converter if you go the Title Case route, since it handles the minor-word rules for you.
Case in URLs
Use lowercase, always. Many web servers treat /Page and /page as different URLs, which means mixed-case links to the same content create genuine duplicates that split ranking signals.
Even where the server normalises case, mixed-case URLs are harder to type, harder to read aloud, and inconsistent with the lowercase convention every major site follows. For building slugs specifically, the URL Slug Generator handles lowercasing, hyphenation and character stripping in one step.
If you already have mixed-case URLs in circulation, the Bulk URL Formatter normalises hostname casing across a list, and the URL Deduplicator collapses entries that differ only by case.
The programming cases
camelCase, PascalCase, snake_case and kebab-case exist because most programming languages disallow spaces in identifiers. Each community settled on a different convention, and following the local one matters more than any argument about which is better.
The one with SEO relevance is kebab-case, since it is the convention for URL slugs. Google has been explicit that hyphens are read as word separators while underscores are not — so best-running-shoes reads as three words and best_running_shoes may read as one token.
That single distinction is why kebab-case rather than snake_case is the right choice for URLs, file names for images, and anything else search engines parse.
Why UPPERCASE hurts readability
Lowercase letters have distinctive shapes — ascenders, descenders, varying heights — that readers use to recognise word shapes without reading letter by letter. Capitals are uniform rectangles, which removes those cues.
The practical result is that all-caps text is read measurably more slowly, and the effect compounds over longer passages. It is fine for a short label or an acronym and poor for a heading, and genuinely bad for a paragraph.
It also reads as shouting in most digital contexts, which is a tone problem separate from the legibility one.
How the conversions handle edge cases
Sentence case lowercases everything, then capitalises the first letter of each sentence detected by terminal punctuation. It does not know your proper nouns, so names and brands need restoring by hand.
Title Case leaves minor words lowercase except when they are the first or last word. The programming cases strip all non-alphanumeric characters before joining, so punctuation and symbols are discarded rather than encoded.
All conversion happens in your browser — nothing you paste is transmitted or stored.
Frequently asked questions
Should headings use Title Case or sentence case?
Both are valid conventions — Title Case follows US publishing style, sentence case follows UK and most modern web style guides. Consistency across your site matters far more than which you pick.
Why should URLs be lowercase?
Many servers treat /Page and /page as different URLs, creating duplicate pages that split ranking signals. Lowercase is also the universal web convention and easier to type and read.
Hyphens or underscores in URLs?
Hyphens. Google treats hyphens as word separators and underscores as joiners, so best-running-shoes reads as three words while best_running_shoes may be read as one.
Does sentence case fix my proper nouns?
No. Sentence case lowercases everything then capitalises sentence starts, so names, brands and place names come back lowercase and need restoring manually.
Is all-caps text bad for readability?
For anything longer than a short label, yes. Capital letters are uniform in shape, which removes the word-shape cues readers rely on, making all-caps text measurably slower to read.