Text Case Converter
Convert text to uppercase, lowercase, sentence case, English title case, or capitalized words. Keep your original text and copy the result.
Choose Transformation Mode
How to Use the Text Case Converter
This tool converts text cleanly without mutating your source text or sending data across the network. Follow these simple steps:
Paste Your Text
Enter or paste your text into the editable “Original text” panel on the left.
Choose a Transformation
Click one of the five mode buttons above: UPPERCASE, lowercase, Sentence case, English Title Case (Basic), or Capitalize Each Word.
Copy or Download
Review the converted text on the right, then click “Copy result” or “Download TXT” to save it.
Understanding the Five Conversion Modes
UPPERCASE
Converts every letter into its uppercase equivalent using Unicode-aware native JavaScript mapping (text.toUpperCase()). Numbers, symbols, punctuation, and emoji remain unchanged.
lowercase
Converts all uppercase letters into their small lowercase counterparts using native Unicode casing (text.toLowerCase()). Useful for cleaning shouty email threads, normalizing filenames, and standardizing data inputs.
Sentence case
Lowercases the text, then capitalizes the first cased letter of each detected sentence. Sentence boundaries are detected using standard sentence punctuation (. ! ?) and line breaks, assisted by modern browser sentence segmentation (Intl.Segmenter) with a documented regex fallback.
English Title Case (Basic)
A rule-based conversion that capitalizes the first and last word of each line and all other words, except for a documented list of interior minor words (a, an, the, and, but, or, nor, for, in, on, at, to, of, by) which remain in lowercase. Hyphens, contractions, and accents are properly preserved.
Capitalize Each Word
Lowercases each word and capitalizes its first cased character. Word boundaries use standard word segmentation. Contractions with internal apostrophes (don't) are treated as single words, and hyphenated terms (state-of-the-art) capitalize each component segment.
Real Input & Output Comparison
See how each transformation behaves on mixed-case input with multiple sentences, punctuation, and exclamations:
hello WORLD. this is a TEST!
HELLO WORLD. THIS IS A TEST!
hello world. this is a test!
Hello world. This is a test!
Hello World. This Is a Test!
Hello World. This Is A Test!
Title Case vs. Capitalize Each Word
While both modes capitalize headings, they serve different editorial purposes:
Applies deterministic rules: capitalizes the first and last word of each line and all other words, while keeping a documented list of interior minor words (a, an, the, and, but, or, nor, for, in, on, at, to, of, by) in lowercase. Ideal for article titles, book names, and chapter headings.
Applies a mechanical rule: capitalizes the initial letter of every single word without exception, regardless of position or whether a word appears in a minor-word list. Best for database records, tabular columns, proper names, and form field values where strict uniformity is preferred.
This deterministic algorithm provides a fast, predictable baseline, but does not claim to fully follow AP, APA, MLA, or Chicago rules. In formal publishing, ambiguous word roles (such as “to” functioning as an infinitive marker vs. preposition, or prepositions acting as adverbs in phrasal verbs like “Log In” vs. “in the room”), proper names with internal capitals (McDonald, iPhone), acronyms (NASA, HTML), and style-specific rules (such as Chicago capitalizing four-letter prepositions like With or From) may require manual review.
Limitations: Acronyms, Proper Names & Unicode
Acronyms & Abbreviations
Converting text to lowercase, sentence case, or capitalized words normalizes letters across the board. Consequently, acronyms like NASA, HTML, or API will become Nasa or html. Always review acronyms after conversion.
Names with Internal Capitals
Proper nouns with camel-cased or prefix-based capitalization (such as McDonald, O'Connor, or van Gogh) will be lowercased after the first letter. Manual adjustments may be required for surnames and trademarks.
Unicode Character Length Expansion
In standard Unicode, some characters do not have a single-character uppercase match. For example, the German sharp s (ß in straße) expands to SS (STRASSE), increasing character count from 6 to 7.
Hyphenated Word Treatment
In “Capitalize Each Word” mode, hyphenated terms like state-of-the-art capitalize each segment (State-Of-The-Art). Contractions like don't preserve their internal apostrophe and lowercase tail (Don't).
In-Browser Processing & Text Confidentiality
Many online converters transmit your text over the internet to remote servers, logging text snippets or using third-party APIs. This tool takes the opposite approach:
Frequently Asked Questions
Does the converter modify my original text?▼
Never. The “Original text” box remains exactly as you entered it. Every transformation calculates a fresh output displayed in the read-only “Converted text” panel, so you never lose your starting draft.
Can I restore my text if I accidentally clear it?▼
Yes. When you click “Clear text”, an Undo bar appears for 10 seconds allowing you to restore your previous text and active mode with a single click. For inputs over 100 characters, a confirmation dialog also helps prevent accidental clearing.
What is the maximum amount of text I can convert at once?▼
You can enter up to 500,000 Unicode characters. If your text exceeds this threshold, live calculation is paused to keep your browser fast and responsive. Your text is never truncated, and you can edit or trim it back under the threshold anytime.
What is the difference between Title Case and Capitalize Each Word?▼
English Title Case (Basic) is rule-based: it capitalizes the first and last word of each line and all other words, except for a documented list of interior minor words (such as “a”, “an”, “the”, “and”, “in”, “of”, and “to”) which remain in lowercase. In contrast, “Capitalize Each Word” capitalizes the first letter of every single word indiscriminately, regardless of position or whether it appears on a minor-word list. Neither mode parses grammatical parts of speech.
How does Sentence case handle punctuation and quotes?▼
Sentence case detects sentence boundaries after periods, question marks, exclamation points, and newlines. If a sentence begins inside quotation marks or parentheses (e.g. “hello world.”), the converter finds the first letter inside the punctuation and capitalizes it correctly (“Hello world.”).
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