Capitalization Checker
Paste your text and the checker highlights every lowercase sentence start, every standalone lowercase “i”, and every lowercase day, month or common proper noun, with a one-click Fix beside each and a Fix All for the lot. It works from four rules and a fixed word list, so it is fast but narrow — it does not know names it was not given. Free, no sign-up, and nothing leaves your browser.
How to Use the Capitalization Checker
- Paste your text. Results appear as you type. Everything runs in your browser.
- Read the three numbers. Words, issues found and the rules checked (four).
- Review the highlights. Each problem is shaded in your text, and the list under it shows the lowercase form, the capitalised form and the rule that applies.
- Fix, then reread. Click Fix for one item or Fix All for every one. The corrected text replaces what is in the box, so skim it — the checker can still be wrong about abbreviations it does not know, as explained below.
What It Checks
| Rule | Flags | Example |
|---|---|---|
| Sentence start | a lowercase letter at the start of the text, at the start of any line, or after . ! ? (with any closing quote or bracket) | we talked. → We talked. |
| The pronoun I | a standalone lowercase i, including i’m, i’ve, i’d | i think → I think |
| Days and months | monday to sunday, and january, february, april, june, july, september, october, november, december | tuesday → Tuesday |
| Proper nouns | a list of 32: languages and nationalities (english, french, american), places (london, india, europe), companies and sites (google, wikipedia), holidays (christmas, easter) | london → London |
May, March and August are left out on purpose, because they are ordinary words too (may the verb, march the verb). Matching of days, months and nouns is whole-word and lowercase-only, so a word already capitalised is never touched. When two findings overlap, only the first is kept.
Capitalization Rules It Cannot Check
Most capitalization decisions depend on meaning, so a list cannot make them. These are the usual ones to check yourself:
- Names it does not know. People, small towns, institutions and brands outside the 32-word list pass unchecked. professor okafor and harvard university will not be flagged.
- Seasons. spring, summer, autumn, winter are lowercase in running text; the checker never touches them.
- Titles of works and headings. APA 7 sets titles of articles and books in a reference in sentence case, and headings and in-text titles in title case. Use the Title Case Converter or Sentence Case Converter.
- Job titles. Capitalised before a name (President Okafor), lowercase otherwise (the president) in most styles.
- Terms whose style has changed. AP lowercased internet in 2016, and Chicago’s current edition does too; the tool does not flag either form.
Where It Gets It Wrong
The sentence-start rule treats a period as the end of a sentence unless it follows a known abbreviation (et al., e.g., i.e., cf., Fig., Dr. and similar) or a line-start list marker such as i., so Smith et al. found a trend is left alone. An abbreviation that is not on that list still triggers a false capital. The pronoun rule skips (i), i), i.e. and i-th, but any other standalone i, such as a loop variable, is “fixed” to I. And google used as a verb is flagged as the company. Review the suggestions before you use Fix All, or fix them one by one.
Worked Example
The 24-word sample below gets seven findings, all real. The words after et al. and e.g. are left alone:
Before
i met my friend on tuesday in london. we talked about the french exam. i think et al. found it, e.g. the tuesday result.
Findings (7)
i → I; tuesday → Tuesday; london → London; we → We; french → French; i → I; tuesday → Tuesday
After, correct
I met my friend on Tuesday in London. We talked about the French exam. I think et al. found it, e.g. the Tuesday result.
Which Tool Do You Need?
| If you want to… | Use |
|---|---|
| Fix lowercase sentence starts, I, days, months and common proper nouns | This Capitalization Checker |
| Scan for repeated words, a/an, punctuation spacing and should of | Grammar Checker |
| Find words that are not in a dictionary, with US or UK spelling | Spell Checker |
| Check their/there, affect/effect and other confusable pairs | Commonly Confused Words Checker |
| Convert a whole heading or title to title case or sentence case | Title Case Converter |
Frequently Asked Questions
- What does the capitalization checker look for?
- Four things: a sentence or line that starts with a lowercase letter, a standalone lowercase i, lowercase days of the week and months (except May, March and August), and 32 common proper nouns such as countries, languages, nationalities, companies and holidays.
- Can it find every proper noun?
- No. It only knows its own list, so people’s names, small towns, universities and most brands pass unchecked. Treat it as a first pass and read the draft for names yourself.
- Why are May, March and August not flagged?
- Because they are also ordinary English words — may is a verb, march is a verb and noun, august is an adjective. Flagging them would create constant false alarms, so the tool skips them. Check those three months by hand.
- How do the one-click fixes work?
- Each finding shows the lowercase text, the capitalised version and the rule. Fix changes that single spot in your text; Fix All applies every suggestion at once. The result stays in the box so you can keep editing.
- Why did it capitalise a word after an abbreviation?
- Because it treats a period as the end of a sentence unless the word before it is a known abbreviation such as et al., e.g., i.e., Fig. or Dr.. An abbreviation outside that list looks like a full stop. Undo that one change or fix the items individually instead of using Fix All.
- Should “internet” be capitalised?
- In current practice, no. AP lowercased it in 2016 and Chicago’s current edition does as well, so the tool does not flag the lowercase form. If a publisher’s style still capitalises it, follow that style.
- Is my text uploaded or stored?
- No. The checks run in your browser, and nothing is sent to a server.