Sentence Case Converter

Fix capitalization so every sentence starts with a capital letter.

Input

Result

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The Sentence Case Converter lowercases your whole text and then capitalises the first letter of each sentence. It is the quickest way to rescue a paragraph typed with Caps Lock on, a shouting all-caps notice, or a title that needs to become normal running text.

The rule the converter follows

Every letter is converted to lowercase.
A letter is capitalised if it is the first letter of the text (after any leading spaces), or if it follows a full stop, question mark or exclamation mark plus at least one space or line break.

That is all. The converter does not know which words are names, places, acronyms or the pronoun "I", so it lowercases them like any other word.

Worked example: an all-caps school notice

Input:

WELCOME TO THE ANNUAL SPORTS MEET. ALL STUDENTS MUST REPORT BY 8 A.M. ON FRIDAY! CONTACT MR. IYER FOR DETAILS.

Output:

Welcome to the annual sports meet. All students must report by 8 a.m. On friday! Contact mr. Iyer for details.

Three problems appear, and all come from the rule above. "On" was capitalised because it follows the abbreviation "a.m." and a space. "friday" lost its capital because the tool cannot tell a day name from an ordinary word. "mr." went lowercase for the same reason, while "Iyer" kept a capital only because it follows a full stop. Proofread proper nouns and abbreviations after every conversion.

Cases the converter handles and misses

Handled: sentences after ? and !, sentences that start on a new line after punctuation, and numbered points like 1. apples, which become 1. Apples.
Missed: a line without closing punctuation (headings, list items) does not trigger a capital on the next line; an ellipsis with no following space (then...it) is not treated as a sentence end; and a sentence starting with a quotation mark keeps a lowercase first letter.
Lowercased by design: "I", "NASA", "UPSC", "iPhone" and names like "Delhi" all go lowercase. Accented first letters such as "é" are not capitalised.

Sentence case vs title case for headings

Sentence case is not only for paragraphs. Many publishers and design systems, including the GOV.UK style guide, use sentence case for headings and buttons because it is easier to read than capitalising every word. If your style guide wants headline-style capitals instead, the Title Case Converter capitalises each word. For forms that demand block letters, use the Uppercase Converter, and if you only want everything in small letters, a lowercase converter skips the capitalisation step.

A practical workflow for pasted all-caps text: convert it here, then search the result for names, places, days, months and acronyms and restore their capitals by hand. For a long document, that is still far faster than retyping.

Frequently asked questions

Why did the converter lowercase names and places?

It lowercases everything first and only capitalises the start of each sentence. It has no dictionary of proper nouns, so restore names, places and acronyms by hand.

Why is a word capitalised after an abbreviation like a.m.?

The tool treats any full stop followed by a space as the end of a sentence, so the next word gets a capital.

Does it capitalise the pronoun I?

No. A lone i in the middle of a sentence stays lowercase, so search for it after converting.

Why did a new line not start with a capital?

A capital is only added after a full stop, question mark or exclamation mark. Lines without closing punctuation, such as headings, do not trigger it.

What is the difference between sentence case and title case?

Sentence case capitalises only the first word of each sentence, while title case capitalises the first letter of every word.