Overview
Introduction
Text pasted from all-caps sources, voice transcriptions, or sloppy typing often ends up with inconsistent capitalization across multiple sentences.
Fixing each sentence by hand, finding the start of every sentence and re-casing it, is slow for anything longer than a line or two.
What Is Proper Case Converter?
A converter that splits text into sentences on periods, exclamation marks, and question marks, then capitalizes just the first letter of each sentence and lowercases the rest of that sentence's letters.
It runs entirely client-side as part of this site's String Tools collection, so nothing you paste is ever uploaded to a server.
How Proper Case Converter Works
The tool scans the input for runs of text ending in '.', '!', or '?', lowercases each run, finds its first letter, and uppercases just that one character before reassembling the text with its original punctuation and spacing.
The transformation happens synchronously in JavaScript the moment you type, with no network round trip involved.
When To Use Proper Case Converter
Use it to normalize text that was typed in all caps, pasted from a transcript, or has otherwise inconsistent mid-sentence capitalization.
It's a fast way to get readable sentence-by-sentence capitalization without manually finding and fixing each sentence start.
Often used alongside Case Converter and Title Case Converter.
Features
Advantages
- Processes every sentence in a multi-sentence paragraph, not just the very first one.
- Preserves original spacing and punctuation exactly, only changing letter case.
- Lowercases the remainder of each sentence rather than only capitalizing its first letter, so text arriving in all caps is fully normalized in a single pass.
Limitations
- Abbreviations containing a period (like 'Mr.', 'e.g.', or 'U.S.') are treated as sentence boundaries, which can produce unwanted capitalization after them.
- Proper nouns that should stay capitalized mid-sentence (like names) are lowercased along with the rest of that sentence's letters.
Examples
Best Practices & Notes
Best Practices
- Manually re-capitalize proper nouns and abbreviations after conversion, since the tool lowercases every letter in a sentence except the first.
- Reach for it on shouty or inconsistently cased text rather than well-formed prose, where it would flatten proper nouns that were already correct.
- Search the result for a standalone 'i' afterwards, since the English first-person pronoun is lowercased along with everything else.
Developer Notes
The implementation uses a single global regex, `/([^.!?]*)([.!?]*)/g`, to capture each sentence body and its trailing terminator pair by pair, lowercases the body, locates its first alphabetic character with `search(/[a-z]/i)`, and uppercases only that character before reassembling with the original terminator.
Proper Case Converter Use Cases
- Normalizing all-caps text pasted from another source
- Cleaning up a voice-transcribed paragraph with inconsistent capitalization
- Fixing capitalization in user-submitted comments or reviews before display
Common Mistakes
- Expecting proper nouns like names or places to stay capitalized mid-sentence; they're lowercased along with everything but the sentence's first letter.
- Running text full of abbreviations through it and being surprised by extra capitals after each abbreviation's period.
Tips
- For text full of abbreviations, review the output afterward, since each abbreviation's period is treated as a sentence end.
- Sentence boundaries come from punctuation alone, so a line with no full stop is treated as one sentence however long it runs.