Proper Case Converter: Names, Data and the Excel PROPER Trap
Proper case capitalizes the first letter of every word and lowercases the rest: ronald mcdonald becomes Ronald McDonald. It is the format names and addresses should be stored in, and it is the one format that spreadsheet functions get wrong most often — because real names do not follow the simple rule.
The converter above knows the exceptions. Turn off Smart name rules and it behaves like Excel’s PROPER function, so you can see exactly what the built-in tools do to your data.
What proper case is
Proper case, sometimes written Proper Case, capitalizes the first letter of each word and forces everything else to lowercase. Its job is normalization: taking data that arrived as JOHN SMITH or john smith and turning it into John Smith so it can be merged into a letter, an invoice or an email without looking shouted or careless.
| Input | Proper case |
|---|---|
| JOHN SMITH | John Smith |
| john smith | John Smith |
| jOHN sMITH | John Smith |
| 123 main STREET | 123 Main Street |
| NEW YORK, ny | New York, Ny |
Look at the last row. NY is a state abbreviation and should stay in capitals, but the plain rule lowercases it. That single example is the whole problem with proper case, and the rest of this page is about it.
Proper case is not title case
The two are constantly confused because they look similar on a short phrase.
| Style | Rule | the lord of the rings |
|---|---|---|
| Proper Case | Every word capitalized | The Lord Of The Rings |
| Title Case | Minor words stay lowercase | The Lord of the Rings |
| Sentence case | First word and proper nouns only | The lord of the rings |
| UPPERCASE | Everything capitalized | THE LORD OF THE RINGS |
Use proper case for data — names, cities, street addresses, product names in a column. Use title case for titles. Using proper case on a headline produces The Lord Of The Rings, which no style guide accepts.
Where proper case belongs
| Use | Why |
|---|---|
| A name column in a database | So mail merges do not shout |
| Street addresses | Postal formats expect it |
| City and country fields | Consistency across records |
| Company names in a CRM | Readable in reports and invoices |
| Imported form submissions | People type in every case imaginable |
| Product or category names | Uniform display in a catalogue |
The eight name rules that break plain proper case
Human names are older than the rule. These are the eight patterns that a naive converter gets wrong, and that the Smart name rules option above handles.
| Pattern | Plain rule gives | Correct |
|---|---|---|
| Mc names | Mcdonald | McDonald |
| Mac names | Macarthur | MacArthur |
| O apostrophe | O'brien | O'Brien |
| Hyphenated | Jean-luc | Jean-Luc |
| Nobiliary particles | Ludwig Van Beethoven | Ludwig van Beethoven |
| Roman numerals | Henry Viii | Henry VIII |
| Acronyms and initialisms | Ibm Corporation | IBM Corporation |
| Contractions | Don'T | Don't |
The Mac trap. A rule that capitalizes the letter after every Mac produces MacHine from machine and MacAroni from macaroni. That is why the converter above uses an explicit list of known Mac surnames rather than a blanket rule. Mc is safe to handle by pattern because almost no ordinary English word begins with it.
Why the Excel PROPER function fails
Excel has a built-in proper case function, =PROPER(A1). It applies the plain rule with no exception list, and on real data that produces three specific failures.
| Cell contains | =PROPER() returns | Problem |
|---|---|---|
| IBM | Ibm | Acronym destroyed |
| don't stop | Don'T Stop | Capitalizes after the apostrophe |
| 3rd avenue | 3Rd Avenue | Capitalizes after a digit |
| o'brien | O'Brien | Correct, by accident — same rule as above |
| mcdonald | Mcdonald | No Mc handling |
| new york, ny | New York, Ny | State code lowercased |
Rows two and four are the same behaviour producing a right answer once and a wrong answer once. That is the signature of a rule without exceptions. The full syntax of PROPER and the other two case functions is in our reference on upper and lower case in Excel.
Proper case in every tool
| Tool | Method | Handles name exceptions? |
|---|---|---|
| This page | Paste and click Convert | Yes, with Smart name rules on |
| Excel | =PROPER(A1) | No |
| Google Sheets | =PROPER(A1) | No |
| Microsoft Word | Home > Aa > Capitalize Each Word | No |
| Google Docs | Format > Text > Capitalization > Title case | No |
| Python | text.title() or string.capwords() | No |
| JavaScript | No built-in method | — |
| SQL Server | No built-in function | — |
| CSS | text-transform: capitalize | No — display only |
Two notes on that table. The CSS property changes only how text is drawn, so copying it elsewhere returns the original case — the same trap as the All caps effect in Word, described in changing case in Word. And text.title() in Python has the apostrophe bug: it's becomes It'S. The workaround is in our guide to converting case in Python.
Cleaning a name column, step by step
- Trim first. In Excel,
=PROPER(TRIM(A1))removes leading, trailing and doubled spaces before it capitalizes. - Convert to values. Copy the formula column, then Paste Special > Values over the original. Without this, deleting the source column turns every result into
#REF!. - Fix the acronyms. Filter for the codes you know are in the data — state abbreviations, IBM, USA, PLC, LLC — and uppercase them back.
- Fix the Mc and Mac names. Sort the column and scan; they cluster together alphabetically.
- Spot-check 20 rows. Not the first 20 — pick them from the middle and the end, where the imported data is usually messier.
Or paste the column into the converter above with Smart name rules on, which does steps 1, 3 and 4 in one pass.
When not to use proper case
- On a headline. Use title case; proper case capitalizes of and the.
- On body text. Use sentence case — the rules are in sentence case explained.
- On email addresses. They are conventionally lowercase, and the local part may be case-sensitive.
- On a name someone writes differently. danah boyd and bell hooks are lowercase by their own choice. A converter cannot know that; a human can.
- On usernames or identifiers. Case may be significant to the system reading them.
Need another style? The upper lower case converter on our home page does twelve — UPPERCASE, lowercase, Sentence case, Title Case, camelCase, snake_case and six more — with a live word and character count. Free, no sign-up.
Proper case in Excel, Google Sheets, Python, SQL and JavaScript
Every platform has a proper case function, and every one of them applies the same naive rule: capitalize the letter after any non-letter, lowercase everything else. That is why a proper case converter that knows names beats a built-in function on real data.
| Platform | Proper case method | Result on ronald mcdonald, IBM |
|---|---|---|
| Excel | =PROPER(A1) | Ronald Mcdonald, Ibm |
| Google Sheets | =PROPER(A1) | Ronald Mcdonald, Ibm |
| Python | text.title() | Ronald Mcdonald, Ibm |
| Python (safer) | string.capwords(text) | Ronald Mcdonald, IBM |
| JavaScript | No built-in method | Requires a custom function |
| SQL Server | No built-in function | Requires a user-defined function |
| MySQL | No built-in function | CONCAT(UPPER(LEFT(n,1)),LOWER(SUBSTRING(n,2))) per word |
| Word | Home > Aa > Capitalize Each Word | Ronald Mcdonald, Ibm |
| This page | Smart name rules on | Ronald McDonald, IBM |
Note the second Python row. str.title() lowercases the tail of every word, so IBM becomes Ibm and o'brien becomes O'Brien only by accident. string.capwords() uppercases the first character and leaves the rest alone, which preserves acronyms but also preserves typing mistakes. Neither knows what a name is. The same limits apply when you convert case in Python or in Java.
Cleaning a name column: a five-step method
This is the workflow that turns a messy export into a mailable list. It takes about ten minutes on a few thousand rows.
- Trim first. Leading spaces and double spaces break every case function. In Excel,
=TRIM(A1); in Sheets the same. Do this before any proper case conversion. - Convert to proper case. Paste the column into the proper case converter above with smart name rules on, or use
=PROPER(TRIM(A1))if the names are plain. - Scan for the four failure families. Mc and Mac names, apostrophe names, nobiliary particles, and suffixes such as II, III and Jr. Sorting the column alphabetically groups most of them together.
- Keep an exceptions list. Every real dataset has names no rule handles: deWitt, van der Berg, LaRoche, DeAngelo. Store them in a lookup sheet and apply them last with a VLOOKUP or XLOOKUP.
- Spot-check fifty rows. Not the first fifty, which are usually the cleanest. Take a random sample from the middle and the end of the file.
Never overwrite the source column. Convert into a new column, verify, then replace. Proper case conversion is not reversible: once MacARTHUR has become Macarthur, the original capitalization is gone and no function can recover it.
Proper case vs title case vs sentence case
Three styles get confused constantly because two of them look similar on a short string. They are not the same rule and they are not for the same job.
| Style | Rule | the lord of the rings | Use for |
|---|---|---|---|
| Proper case | Capitalize every word, no exceptions | The Lord Of The Rings | Names, addresses, database fields |
| Title Case | Capitalize significant words only | The Lord of the Rings | Book, film and article titles |
| Sentence case | First word and proper nouns only | The lord of the rings | Body text, web headlines, buttons |
Proper case is the right tool for a name field and the wrong tool for a headline, because it capitalizes of and the. If you are formatting a title, use the title case converter instead and check which words are not capitalized in titles. For running text, sentence case is the default, and the full set of English rules is in our guide to capitalization in writing.
Converting ALL CAPS names to proper case
Legacy systems store names in capitals: MARY SMITH, JEAN-PIERRE DUBOIS. This is the most common reason people look for a proper case converter, and it is the case where acronym protection works against you.
The converter on this page detects it. If the text you paste contains no lowercase letter at all, it treats the whole input as capitalized data and converts every word, so MARY SMITH becomes Mary Smith. If the text is mixed, it protects all-capital words as acronyms, so IBM corporation becomes IBM Corporation rather than Ibm Corporation.
The one situation that still needs a human is an all-capital list that contains a genuine acronym, such as IBM UNITED KINGDOM LTD. There is no signal in the text that separates the acronym from the name, so no converter can be right every time. Convert, then fix the handful of acronyms by hand. The wider question of when capitals help and when they hurt is covered in uppercase vs lowercase and the purpose of capital letters.
Proper case in addresses, companies and job titles
| Field | Raw | Proper case output | Still needs a fix |
|---|---|---|---|
| Street | 14 st. john's road | 14 St. John's Road | None |
| City | newcastle upon tyne | Newcastle Upon Tyne | upon is usually lowercase |
| Company | smith & sons llc | Smith & Sons Llc | LLC should stay capitalized |
| Company | ebay inc | Ebay Inc | Brand is written eBay |
| Job title | head of sales | Head Of Sales | of is usually lowercase |
| Postcode | sw1a 1aa | Sw1a 1aa | Postcodes need UPPER, not proper case |
The pattern is consistent: proper case is correct for personal names and street names, and approximately correct for everything else. Company suffixes (LLC, Ltd, PLC, GmbH, SA), postcodes and country codes belong in uppercase, not proper case, and brand names follow whatever the owner writes.
Frequently asked questions
What is proper case?
Proper case capitalizes the first letter of every word and lowercases the rest. It is used to normalize names, addresses and other data so they display consistently.
What is the difference between proper case and title case?
Proper case capitalizes every word. Title case leaves short articles, conjunctions and prepositions lowercase. The Lord Of The Rings is proper case; The Lord of the Rings is title case.
How do I do proper case in Excel?
Use =PROPER(A1), or better =PROPER(TRIM(A1)). Then copy the results and use Paste Special > Values before deleting the source column.
Why does PROPER turn IBM into Ibm?
Because it has no exception list. It capitalizes the first letter of every word and lowercases everything after it, with no way to recognize an acronym.
Why does PROPER produce Don'T?
It treats the apostrophe as a word separator and capitalizes the letter after it. The same rule gives the correct O'Brien, which is why it is not simply switched off.
How do I capitalize McDonald correctly?
Capitalize the letter after Mc. Use a converter with a Mc rule, or fix them by hand after sorting the column, since they group together alphabetically.
Should van and von be capitalized in a name?
Not in the middle of a full name: Ludwig van Beethoven. When the surname stands alone it is often capitalized: Van Beethoven. Conventions vary by country and by family.
Is proper case the same as capitalize each word?
Yes, they describe the same operation. Proper case is the spreadsheet name for it; Capitalize Each Word is the Microsoft Word name.
The short version
Proper case capitalizes the first letter of every word and is the right format for names and addresses in data. The plain rule breaks on Mc, Mac, O apostrophe, hyphenated names, nobiliary particles, Roman numerals, acronyms and contractions — and Excel’s PROPER function breaks on all eight. Use a converter with exceptions, convert to values before deleting the source, and spot-check the middle of the column rather than the top.