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Convert mixed-case text into clean sentence case in seconds — plus lowercase, UPPERCASE, and Title Case in one tool. Live dual textareas, Copy output, Load example, and Clear. Built for writers, editors, marketers, and support teams.
Also try the Text Repeater, LinkedIn Headline Generator, and more in Text tools.
Last updated: May 19, 2026 · Published: 2026-04-09 · Updated: 2026-05-19
Tip: Sentence case capitalizes the first letter after `.`, `!`, and `?` for cleaner writing and editing workflows.
A sentence case converter fixes capitalization so each sentence starts with one uppercase letter and the rest reads in lowercase — ideal when pasted text arrives in ALL CAPS or random mixed case from PDFs, chats, or old CMS exports.
This Muxgen tool also offers lowercase, UPPERCASE, and Title Case modes. Sentence case capitalizes after period, exclamation, and question mark — all processing runs locally in your browser.
Three simple steps to fix text capitalization.
Add mixed-case content to sentence-input.
Sentence case, lowercase, UPPERCASE, or Title Case buttons.
Copy output into docs, CMS fields, emails, or social posts.
Every control in the sentence case converter component.
Four buttons — sentence, lower, upper, title ConvertMode values.
Textarea id sentence-input — min-height 40; default mixed-case demo.
Read-only id sentence-output — live useMemo result.
Lowercase pass then capitalize after start and . ! ?
Standard input.toLowerCase() and toUpperCase().
Lowercase then word-boundary first-letter uppercasing.
Boolean toggled true at start and after sentence-ending punctuation.
Primary button disabled when output empty.
Sets THIS is MIXED cAsE. hERE is another sentence. WHY not?
Ghost button empties input.
Explains . ! ? sentence boundaries.
How each formatter transforms your input.
First letter of each sentence capitalized — rest lowercase from the lower pass.
Entire string toLowerCase — useful for slugs or CSS keys.
Entire string toUpperCase — emphasis or legacy data inspection.
Capitalize first letter of each word per \b word-boundary regex.
No Generate button — switch modes instantly on same input.
Fast cleanup — human review for proper nouns and brand names.
When to use each mode and how this fits on Muxgen.
Sentence capitalizes after . ! ?; Title capitalizes each word start.
Sentence keeps readable caps; lowercase flattens everything.
This fixes Latin casing; Fancy Text changes Unicode letter shapes.
Casing only — not spelling or style guide enforcement.
Paste legacy ALL CAPS fields → sentence case → paste back.
Normalize mixed paste from tickets before sending replies.
Example outputs for the same sample phrase.
This is an example. Here is another line!
After lower + cap rules
This Is An Example. Here Is Another Line!
Word-boundary caps
THIS IS AN EXAMPLE. HERE IS ANOTHER LINE!
toUpperCase()
this is an example. here is another line!
toLowerCase()
. ! ?
New sentence in toSentenceCase
Sentence case
mode starts sentence
Aligned with the sentence case converter component.
Sentence, lower, upper, and title in one UI.
Resets caps after . ! ?
Instant preview while typing.
Copy output for editing workflows.
Mixed-case demo in one click.
No account; drafts stay local.
Where sentence case conversion saves time.
Fix inconsistent case before publish.
Normalize shouty ALL CAPS drafts.
Clean canned responses and macros.
Readable sentence style from copied notes.
Standardize text moving between systems.
Consistent casing in meta descriptions.
Terms used in the UI and case conversion logic.
Capitalize first letter of each sentence; remainder mostly lowercase.
Major words capitalized — here via word-boundary regex.
Flag in toSentenceCase controlling next letter uppercasing.
sentence | lower | upper | title — selects formatter.
Regex anchor used in toTitleCase replacement.
Random capitals mid-word — common paste problem this tool fixes.
Editorial habits after mechanical case conversion.
Brands and names may need hand fixes after mechanical sentence case.
Body copy usually reads better in sentence case.
Compare four outputs on the same mixed string.
Save sentence output before testing Title Case on long drafts.
Store original paste until you verify converted tone.
Normalize case then repeat lines for templates.
Habits that pair with live output and Copy output.
Default mode matches most editorial needs.
Abbreviations like e.g. may capitalize the next letter — edit if needed.
Then pass to URL slug tools on Muxgen utility pages.
Avoid mixing two client drafts in one session.
Use Copy output for CMS paste fields.
Generate heading line separately from body sentence case.
toSentenceCase rules, Title Case regex, proper nouns, punctuation triggers, and privacy.
Explore more tools in the directory.
Repeat lines with separators after you normalize case.
Unicode styles once capitalization is cleaned.
Bold Unicode for bios after sentence-case cleanup.
Italic mathematical Unicode for emphasis lines.
Professional headlines with tone and length caps.
Reverse text for puzzles after editing case.