Sentence Case Converter
Turn shouting text back into readable prose.
Sentence case means exactly one capital letter at the beginning of each sentence, with everything else lowercase apart from words that are always capitalized. It is the normal style for body text, product descriptions, and increasingly for user interface labels and headings.
The common reason to reach for this tool is text that arrived in the wrong case: a paragraph typed with caps lock on, a heading copied from a design that used all capitals, or a spreadsheet column where someone shouted every entry. Reading such text is measurably slower, and pasting it into a document makes the whole page look broken.
This converter lowercases the input and then restores capitals where sentences begin — after a full stop, question mark, or exclamation mark, and at the start of each new line. The English pronoun "I" is restored along with its contractions, since lowercasing it is the mistake people notice first.
Examples
| What it handles | Input | Output |
|---|---|---|
| All caps to sentence case | HELLO WORLD. THIS IS A TEST. | Hello world. This is a test. |
| Question and exclamation marks | what? YES! ok then | What? Yes! Ok then |
| The pronoun I is restored | i think i am right | I think I am right |
How it works
The entire input is lowercased first, which normalizes ALL CAPS and random mixed case in one pass. A pattern then finds the start of the text, the position after each sentence-ending punctuation mark followed by whitespace, and the start of each new line, capitalizing the first letter it finds in each position. Closing and opening punctuation around that boundary is stepped over rather than treated as a wall, so quoted dialogue keeps working: in `He said. "Yes." Then left.` the capital lands inside the quotation marks and the sentence after the closing quote is still recognized. The same tolerance covers brackets and list markers, so `(hello) world` and a line beginning `- like this` are capitalized too. Finally the standalone pronoun "I" and its contractions — I'm, I've, I'll, I'd — are restored to uppercase. Proper nouns cannot be detected automatically, so names, brands, and places will need a manual pass after conversion.
When people use it
- Fixing a paragraph typed with caps lock left on.
- Converting all-caps headings into readable sentence case.
- Normalizing imported spreadsheet or CRM fields written in capitals.
- Cleaning subtitles and transcripts that arrived fully capitalized.
Frequently asked questions
- Will it capitalize names and places?
- No. Detecting proper nouns reliably would require a dictionary and would still misfire on ordinary words. The tool handles sentence starts; give names a quick manual pass afterwards.
- What happens to text after a colon or semicolon?
- It stays lowercase. In English a colon does not normally start a new sentence, so capitalizing there would be wrong more often than right.
- Does it handle abbreviations like "e.g."?
- Partially. A full stop followed by a space is treated as a sentence boundary, so "e.g. this" will capitalize "this". Review abbreviation-heavy text after converting.
- Are accented characters affected?
- They are lowercased and capitalized correctly using locale-aware rules, so é becomes É and back without corruption.