Sentence Case Converter
Turn shouted or inconsistently capitalised text back into normal prose: one capital at the start of each sentence, everything else lowered, and the standalone pronoun "I" put back.
That last part is what separates this from a plain lowercase pass. Most converters leave you with "i think i am ready", which is visibly wrong; this one restores "I" and its contractions automatically.
Is it a heading rather than a sentence? Use title case
Sentence Case Examples
Including the pronoun and line-break behaviour that most converters skip.
| Input | Output | What it shows |
|---|---|---|
| THIS IS ALL CAPS. IT SHOULD NOT BE. | This is all caps. It should not be. | Each sentence gets exactly one capital. |
| i think i am ready. i am. | I think I am ready. I am. | The standalone pronoun "I" is restored throughout. |
| i'm sure i'll be fine | I'm sure I'll be fine | Contractions of "I" are restored too. |
| first line second line | First line Second line | A line break starts a new sentence, so each line gets a capital. |
| what? really! yes. | What? Really! Yes. | Question and exclamation marks both end a sentence. |
| THE NASA REPORT WAS CLEAR. | The nasa report was clear. | Acronyms are flattened — NASA becomes Nasa and needs restoring by hand. |
| hello... is anyone there? | Hello... Is anyone there? | An ellipsis is three full stops, so the next letter is capitalised. |
| mixed CASE input HERE. | Mixed case input here. | Interior capitals are removed rather than preserved. |
How Sentence Case Is Applied
Lower everything, capitalise the sentence starts, then repair the pronoun. Each step has a specific job.
The text is lowered first
This is what fixes all-caps input. Without it, a paragraph typed in caps lock would keep every capital and the conversion would do nothing useful.
Sentence starts are detected by punctuation
A capital is applied at the very start of the text and after any full stop, question mark or exclamation mark followed by whitespace — and after a line break, so each line of a list gets its own capital.
The pronoun "I" is restored
A standalone lowercase "i" is raised, along with the contractions I'm, I'll, I've and I'd. Skipping this is the single most obvious flaw in naive sentence-case output.
Everything else is left alone
Digits, punctuation, spacing and line breaks pass through untouched, so the shape of your paragraph is unchanged.
Sentence Case vs the Alternatives
The same all-caps paragraph through each conversion. Only the first row produces readable prose.
Shared input: THE MEETING STARTS AT NOON. PLEASE BRING YOUR NOTES.
| Transformation | Result | Reach for it when |
|---|---|---|
| Sentence case | The meeting starts at noon. Please bring your notes. | It is prose and should read normally. |
| lowercase | the meeting starts at noon. please bring your notes. | You want everything lowered, capitals included. |
| Title Case | The Meeting Starts At Noon. Please Bring Your Notes. | It is a heading rather than a sentence. |
| iNVERSE cASE | the meeting starts at noon. please bring your notes. | The capitalisation is exactly inverted. |
What Sentence Case Cannot Know
Sentence boundaries and proper nouns are genuinely ambiguous without a dictionary. Here is where to check the output.
Abbreviations look like sentence ends
"Dr. Smith" and "e.g. this" contain full stops mid-sentence, so the following letter is capitalised. Scan for abbreviations after converting a paragraph that uses them.
Proper nouns are not detected
Names, places and brands are lowered along with everything else unless they start a sentence. There is no dictionary behind the conversion.
Acronyms are flattened
NASA becomes Nasa, HTML becomes Html. The lowering pass cannot tell an acronym from a shouted word.
Decimal numbers can trigger a capital
"version 1.2 beta" has a full stop between digits. It is not followed by whitespace, so no capital is applied — but a full stop followed by a space and a letter always is.
Where Sentence Case Is the Right Choice
Sentence case has quietly become the default in most modern interface and editorial style guides.
Interface copy
Google, Apple and Microsoft all specify sentence case for interface text and most headings. It reads faster than title case and is far easier to apply consistently.
Email subject lines
Sentence case subject lines read as personal rather than promotional, which is usually what you want in one-to-one email.
Documents and reports
Converting a section typed in caps back to sentence case restores its readability in one paste, with no retyping.
Support tickets and forms
Text pasted from a phone keyboard often arrives with erratic capitalisation. One conversion makes a ticket queue consistent.
Reasons to Use Sentence Case
Fixing caps-lock accidents
A whole paragraph typed with caps lock on is repaired in one paste, capitals included, rather than retyped.
Cleaning pasted content
Text from slides, posters and PDFs often arrives fully capitalised. Sentence case makes it usable as body copy.
Normalising user submissions
Form submissions come in every capitalisation imaginable. Converting them makes a list of entries look deliberate.
Matching a modern style guide
If your style guide specifies sentence case for headings, this converts an older title-case document in one pass.
Frequently Asked Questions
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