Sentence case converter
Turn inconsistent capitalization into sentence, title, capital, lower, or upper case while keeping the original wording and punctuation intact.
Text to convert
Required. Up to 16,000 characters. Line breaks and punctuation are preserved.
Sentence case is the default. Other modes change capitalization only; they do not rewrite wording.
Converted result
Automatic case conversion cannot reliably infer every proper noun from heavily distorted text. Review names, brands, acronyms, and language-specific capitalization before publishing.
Sentence case conversion ready: 104 characters, 14 words, 2 sentences.
How to use this sentence case converter
What this calculator does
This converter changes capitalization without changing the words, punctuation, spacing, or line breaks you provide. Its default Sentence case mode lowers ordinary words and capitalizes the first word of each detected sentence or line. It can also produce Title case, Capital case, lowercase, or UPPERCASE. It is designed for cleanup and formatting, not grammar correction: it does not rewrite sentences, verify spelling, or reliably identify every proper noun in text whose original capitalization has been destroyed. Microsoft's guidance describes sentence-style capitalization as using lowercase for ordinary words while retaining capitalization for the first word and proper nouns.
When to use it
Use the converter when you need to clean up headings copied from an all-caps system, normalize inconsistent text from spreadsheets or forms, prepare interface labels that follow sentence-style capitalization, or compare how the same wording looks under several capitalization conventions. It is especially useful as a quick first pass before editorial review when large blocks of text have inconsistent casing.
How to calculate
- The calculator opens with a complete demonstration text and immediately shows the converted result. The example Excel workbook is also available from the first screen.
- Replace the demonstration in Text to convert with your own text. The result updates live as you type, up to the 16,000-character limit.
- Choose a Case style. Sentence case is the default; Title case uses major-word capitalization, Capital case starts every word with a capital, lowercase lowers all cased letters, and UPPERCASE raises them.
- Read Converted text and the live Characters, Words, and Sentences counts. Review names, acronyms, brands, and special terminology before using the text in a final document.
- Select Download Excel to create a current-state workbook containing the source text, selected case style, converted text, and text counts. Reset clears the demonstration and all calculated content; Excel export stays unavailable until complete valid text is entered again.
Input guide
Text to convert is a required text field. It accepts ordinary Unicode text, punctuation, spaces, and line breaks, with a maximum of 16,000 characters. A realistic input is “wELCOME TO THE SENTENCE CASE TOOL. this SAMPLE shows how consistent capitalization improves readability!” Changing any character changes the conversion directly because the converter does not substitute synonyms or alter punctuation. An empty field is invalid. A common mistake is assuming a case tool can reconstruct every proper noun from an all-uppercase source; if a name has lost its intended casing, review it manually after conversion.
Case style is a required selection with five options. Sentence case detects sentence starts and lowercases ordinary words; Title case applies a major-word style with common short articles, conjunctions, and prepositions lowercased when they are not first or last; Capital case capitalizes each word; lowercase and UPPERCASE perform direct Unicode case conversion. Changing this selection changes only capitalization. The main interpretation mistake is treating a style convention as a grammar rule: organizations and publications may apply different exceptions.
Output guide
Mode shows the selected capitalization style, and the Active style card mirrors the same setting. Characters is the number of Unicode code points in the source, including spaces and punctuation. Words counts contiguous letter-or-number word tokens, including words with internal apostrophes or hyphens. Sentences estimates sentence units using sentence-ending punctuation and non-empty line structure; it is a structural count, not linguistic sentence parsing. A zero count appears only in the cleared or invalid empty state; larger counts mean the source is longer, not that it is better or worse. Converted text is the exact capitalization conversion generated from the source and selected mode. The text result is a deterministic transformation, while the sentence count is a practical estimate for display and export.
Worked example
The startup example contains 104 characters, 14 words, and 2 detected sentences. With Sentence case selected, “wELCOME TO THE SENTENCE CASE TOOL.” becomes “Welcome to the sentence case tool.” The second sentence starts after the full stop, so “this SAMPLE...” becomes “This sample...”. The first-open result is therefore: “Welcome to the sentence case tool. This sample shows how consistent capitalization improves readability!” The Excel workbook records the same source, selected mode, converted output, and counts, so the on-screen result and exported workbook are generated from the same canonical state.
Learn more
For a concise editorial definition and examples of sentence-style capitalization, consult the Microsoft Style Guide on capitalization. Use the house style required by your publication, organization, course, or product when it differs from this converter's deterministic rules.
How sentence case works in practice
Sentence case is a restrained capitalization convention. The first word receives an initial capital, while ordinary words remain lowercase unless another rule requires capitalization. For headings and titles, some style guides also capitalize the first word after a colon. Google's developer documentation recommends sentence case for headings and titles because descriptive, consistently cased headings improve navigation and scanning; see its guidance on headings and titles.
This converter uses a deterministic text-processing rule rather than a language model. That distinction matters. The sentence-mode logic preserves a small set of common acronyms, weekday and month names, language adjectives used in the guide, and some internal mixed-case forms. However, text written entirely in capitals often removes the evidence needed to distinguish an arbitrary acronym or proper noun from an ordinary word. For example, a person can recognize that NASA is an acronym from knowledge, but a generic casing rule cannot safely infer that every short uppercase token should remain uppercase without also preserving ordinary all-caps words. The safest workflow is to convert first, then review proper nouns and acronyms.
Title case, capital case, lowercase, and uppercase
Title case is useful for conventional English-language titles. This implementation capitalizes the first and last word and major words in between, while common short articles, conjunctions, and prepositions are normally lowercase. Capital case is mechanically simpler: every detected word begins with a capital letter. lowercase and UPPERCASE use direct Unicode case conversion and are useful for normalization, search preparation, or deliberate display styles. Because house styles differ, use these modes as formatting tools rather than as a substitute for a publication's style sheet.
Readability and editorial review
Government writing guidance also favors minimal capitalization. The Australian Government Style Manual defines sentence case as capitalizing the first word while keeping other words lowercase unless they are proper nouns, and it recommends using minimal punctuation and capitalization to support readability. Its capitalisation and punctuation guidance is a useful reference when preparing headings, labels, and general public-facing content.
After conversion, check names of people and organizations, geographic names, product names, acronyms, programming identifiers, and words from languages with different capitalization conventions. Also verify text around colons, dashes, quotations, abbreviations, and unusual punctuation. The converter intentionally leaves wording and punctuation untouched, so any grammar, spelling, or punctuation issue in the source remains in the result.