Punctuation Checker: find and fix punctuation mistakes

How to use the punctuation checker

Paste or type your text into the box. The punctuation checker reads it as you type and shows the same text underneath with every finding underlined. Tap an underlined part to see what is wrong, the rule behind it, and the corrected version. You can check a single sentence or a whole essay of up to 20,000 characters, and nothing you type leaves your browser.

1. Add your text. Not sure what to expect? Tap Try a sample to load a short note with a mistake of almost every kind.
2. Read the underlines. A solid red underline is an error: a clear mistake with a safe fix. A dashed yellow underline is a suggestion: something that is often wrong but depends on what you mean, so the decision is yours.
3. Fix one at a time, or all at once. Apply corrects the finding you have open. Fix all errors corrects every error in one go and never touches a suggestion. Undo takes back the last fix, and Ignore hides a finding you disagree with.
4. Copy the result. Copy text puts the corrected text on your clipboard.

The buttons and settings above the result change what is checked:

• Check. All rules is the default. Each of the other buttons narrows the check to one kind of mark and shows how many findings it has, so you can work through commas first, then apostrophes, and so on.
• Style. American puts commas and periods inside closing quotation marks and expects a comma after e.g. and i.e. British does neither. See American and British punctuation below.
• Oxford comma. Off by default, because both ways are correct. Choose Require it or Avoid it and the checker holds every list to your choice.
• Dashes. Pick the dash the checker should suggest: an em dash without spaces or an en dash with spaces.
• Show suggestions. Untick it to see errors only.

What the punctuation checker checks

The checker applies 40 rules, listed below with a sentence that breaks each one and the same sentence after the fix. It is a rule-based tool, not an AI: it does not understand what your text means, it only recognizes patterns it can be sure about. That is why it separates errors from suggestions, and why a result with no findings is a good sign but not proof that a text is perfect.

The checker leaves certain things alone on purpose: web and email addresses, file names, numbers such as 3.5 and 1,000, times such as 5:30 p.m., and abbreviations such as Dr., U.S. and a.m. A period inside one of these is not the end of a sentence, and a comma inside a number is not a comma that needs a space.

Comma checker: the comma rules it applies

Most of the checker’s work is commas: 17 of its 40 rules. To use the tool as a comma checker, tap Commas only, or open it that way with this link. Here are the main rules, each with a sentence the checker corrected and a guide that explains the rule in depth.

After an introductory word or phrase

A word or phrase that opens a sentence and comments on the rest of it takes a comma.
Before: However the store was already closed.
After: However, the store was already closed.

The checker knows a fixed list of such openers, including however, furthermore, unfortunately, for example, in fact, on the other hand, yes, no and well. It also knows when these words are not openers, so “However hard he tried, the jar stayed shut” and “No one knew” are left alone. After words where the comma is a matter of style, such as therefore or of course, it only makes a suggestion. Guides: comma before or after however, comma after for example, comma after therefore.

Around a word that interrupts the sentence

When however or for example sits in the middle of a sentence, it needs a comma on both sides. One comma is the usual slip. Guide: comma before for example.
Before: The plan, however was never finished.
After: The plan, however, was never finished.

Comma splices

A comma splice is two complete sentences joined by a comma alone. The clearest case uses however, and the checker marks it as an error.
Before: I wanted to go, however, I was too tired.
After: I wanted to go; however, I was too tired.

Without such a signal word the checker cannot be certain that both halves are full sentences, so it only suggests a fix. A semicolon is one repair. A period, or a comma with and, but or so, works just as well.
Before: The store was closed, we went home.
After: The store was closed; we went home.

For a closer look at sentences that run together, use the run-on sentence checker, and read our guide to common comma mistakes.

Punctuation in compound and complex sentences

A compound sentence joins two complete sentences with and, but, or, so or yet, and a comma goes before the joining word. The checker flags a missing one as a suggestion, because two very short sentences can go without it.
Before: The rain stopped at noon and we walked to the lake.
After: The rain stopped at noon, and we walked to the lake.

A complex sentence has a main clause and a dependent clause that starts with a word like because, when, if or although. If the dependent clause comes first, a comma follows it: “When the bell rang, the students left.” If it comes last, there is usually no comma: “The students left when the bell rang.” A compound-complex sentence uses both rules at once. The checker handles the compound part and the comma splices. It suggests the comma after an opening clause when it can find where the clause ends, and leaves the harder cases to you. Guides: commas with and, but, or, so, comma before and, comma before subordinate clauses.

that and which

No comma goes before that when it introduces what someone said, thought or meant.
Before: She said, that the train was late.
After: She said that the train was late.

Which is the opposite. In American English it usually adds extra information and takes a comma. If the information is essential, most American editors use that with no comma. Guides: comma before that, comma before which.
Before: We took the old road which is closed in winter.
After: We took the old road, which is closed in winter.

e.g., i.e., etc. and such as

In American style a comma follows e.g. and i.e. At the end of a list, etc. follows a comma and never needs and. And no comma follows such as. Guides: comma after e.g., comma before etc., comma before such as.
Before: Bring a snack, e.g. an apple or some nuts.
After: Bring a snack, e.g., an apple or some nuts.
Before: We sell pens, paper, and etc.
After: We sell pens, paper, etc.
Before: Bring warm clothes such as, a hat and gloves.
After: Bring warm clothes such as a hat and gloves.

Dates, places and names

In a month-day-year date, the year is set off by commas. The same goes for a state after a city. And a name you speak to directly gets a comma. Guides: comma after a city and a state, comma before a name you address, comma after best regards.
Before: The shop opened on March 3 2021 and closed a year later.
After: The shop opened on March 3, 2021, and closed a year later.
Before: She moved from Austin, Texas to a small town in Ohio.
After: She moved from Austin, Texas, to a small town in Ohio.
Before: Thanks Sam!
After: Thanks, Sam!

The Oxford comma

The Oxford comma, or serial comma, is the comma before and or or in a list of three or more. The Chicago Manual of Style, APA and MLA use it. AP style leaves it out of simple lists. Neither is wrong, so the checker ignores it until you choose. A comma before and that joins two full sentences is not an Oxford comma, and the checker keeps it either way. Guide: comma before and in a list.

With Require it:
Before: We ordered soup, salad and bread.
After: We ordered soup, salad, and bread.

With Avoid it:
Before: We ordered soup, salad, and bread.
After: We ordered soup, salad and bread.

Comma rules chart: the 8 rules you need most

Eight rules cover almost every comma you will ever write, and three more tell you which commas to delete. The chart shows each rule as a pattern with one example. Save it, print it or pin it for later.

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1. After an opening word or phrase. After the movie, we got pizza. The same goes for however, yes, well and clauses that start with if or when.
2. Before and, but, or, so when a full sentence follows. I called, but nobody answered.
3. Between the items in a list. We need eggs, milk, and bread. The last comma is the Oxford comma.
4. Around extra information. Sam, my neighbor, bakes bread. Take the extra part out and the sentence still works.
5. Between two describing words. It was a long, cold winter. The test: you could say “long and cold.”
6. When you speak to someone. Let’s eat, Grandma!
7. In dates and places. On May 2, 2020, we moved to Austin, Texas, for good. A comma follows the year and the state as well.
8. Before a quotation. She smiled and said, “Come in.”

And the three commas to delete: the comma that joins two full sentences on its own (It was late, we left), the comma between a subject and its verb (The old dog, barked all night), and the comma before that (He said, that he was tired).

Apostrophe checker

An apostrophe does two jobs in English: it marks the missing letters in a contraction (don’t, it’s) and it shows possession (the dog’s bowl). It does not make a plural. Tap Apostrophes only, or use this link, to run the tool as an apostrophe checker. It looks for four things.

• Contractions typed without the apostrophe. Only spellings that are never a word on their own are flagged. Were, well, shell, ill and wed are real words, so the checker does not guess that you meant we’re or we’ll.
  Before: I dont think theyre ready.
  After: I don't think they're ready.
• its and it’s, in clear cases. It’s means it is or it has; its shows that something belongs to it. A quick test: if you can say it is in its place, write it’s.
  Before: Its a long way to the coast.
  After: It's a long way to the coast.
  Before: The dog chased it's own tail.
  After: The dog chased its own tail.
• A plural with an apostrophe after a number word.
  Before: We adopted two cat's.
  After: We adopted two cats.
• Decades. This one is a suggestion, since a few publications still print the apostrophe.
  Before: The house was built in the 1990's.
  After: The house was built in the 1990s.

What it cannot do is find a possessive that has no apostrophe at all, as in the dogs bowl. A sign that reads apple’s for sale is also beyond it, because the apple’s color is perfectly correct. For those, ask whether something belongs to the word. If nothing does, it is a plain plural and needs no apostrophe.

Semicolon checker (and colons)

A semicolon has three standard uses. It joins two complete sentences that belong together: “The rain stopped; the sun came out.” It comes before however, therefore and similar words when they link two sentences. And it separates the items of a list when the items contain commas of their own: “Paris, France; Lima, Peru; and Austin, Texas.” Choose Semicolons & colons, or open this link, to use the tool as a semicolon checker.

• Capital letter after a semicolon. A semicolon does not end the sentence, so the next word stays lowercase unless it is a name.
  Before: The rain stopped; The sun came out.
  After: The rain stopped; the sun came out.
• Semicolon before and or but. A comma is the normal mark there, so the checker suggests one. In a long sentence that already has commas, the semicolon is fine, and the checker says nothing.
  Before: We waited for an hour; but nobody came.
  After: We waited for an hour, but nobody came.

A colon introduces a list, an explanation or a quotation, and what comes before it should be a complete sentence. That is why a colon straight after a verb or a preposition is flagged as a suggestion. A colon at the end of a line that leads into a list set out below it is left alone. Guides: how to use semicolons and how to use colons.
Before: The colors are: red, green and blue.
After: The colors are red, green and blue.

Quotation marks and brackets

The checker first makes sure every quotation mark and every bracket has a partner. An opening mark that is never closed is underlined, but not fixed for you: only you know where the quotation ends. It then looks at the marks around the quotation. Guide: commas with quotation marks.

• A comma between the quotation and the speaker. After a quoted question, the question mark replaces the comma.
  Before: She said "We are leaving now."
  After: She said, "We are leaving now."
  Before: "Are you coming?", he asked.
  After: "Are you coming?" he asked.
• Commas and periods inside the closing mark (American style).
  Before: She called it "a small win", and we agreed.
  After: She called it "a small win," and we agreed.
• One kind of mark. Text pasted together from several places often mixes straight marks (") with curly ones (“ ”). The checker offers to make them all match.
• A comma before an opening bracket. The comma belongs after the closing bracket.
  Before: After the show, (which ran long) we walked home.
  After: After the show (which ran long), we walked home.

American and British punctuation

American and British English share almost all of their punctuation. The few differences are matters of convention, not of right and wrong, and the Style setting covers the ones a rule can check. The table shows the same typed text under both settings.

The best-known difference is the first one. American style places a comma or period inside the closing quotation mark whether or not it belongs to the quoted words. British style places it by sense: inside if it is part of the quotation, outside if it is not. In both, a question mark goes inside only when the quoted words are the question, and colons and semicolons go outside.

Some differences are not checked, because either form may be exactly what you intend:

• American writing uses double quotation marks first and single marks for a quotation inside a quotation. Many British publishers do it the other way round.
• American English writes Mr., Mrs. and Dr. with a period. British English usually writes Mr, Mrs and Dr without one.
• An American date is written month first, with commas: March 3, 2021. A British date is written day first, with none: 3 March 2021.
• In British English, which often introduces essential information with no comma, where American editors prefer that. See comma before which in British English.

Hyphens and dashes

A hyphen (-) joins words or parts of words: well-known, mother-in-law. A dash separates parts of a sentence, a little more strongly than a comma. The hyphen is the easy key to reach, so dashes are often typed as hyphens. The checker corrects two habits: two hyphens in a row, and a single hyphen with a space on each side.
Before: The view--all hills and sky--was worth the climb.
After: The view—all hills and sky—was worth the climb.

With the en dash setting:
Before: The view - all hills and sky - was worth the climb.
After: The view – all hills and sky – was worth the climb.

The em dash without spaces is the form in the Chicago Manual of Style, APA and MLA. AP style puts a space on each side of the dash. The en dash with spaces is common in British publishing. Hyphens inside compound words, number ranges and command-line options such as --help are left alone.

Spacing and the end of the sentence

The simplest rules catch the most common typing slips. No space goes before a comma, period or question mark, and one space goes after it. A sentence starts with a capital letter and ends with a closing mark. One mark is enough, an ellipsis has three dots, and a single space follows a period, which is what AP, APA, Chicago and MLA all ask for.
Before: We left early , but the road was busy .
After: We left early, but the road was busy.
Before: The store was closed. we went home
After: The store was closed. We went home.

A sentence such as “Dr. Lee arrived at 5:30 p.m. and paid $3.50.” passes untouched: the checker knows that the periods in Dr. and p.m., the colon in 5:30 and the point in $3.50 are not sentence punctuation.

What a rule-based checker can and cannot do

This tool does not use a language model, and it does not send your text anywhere. It runs a fixed list of rules in your browser. That makes it fast, private and predictable: the same text always gives the same result, and every finding names the rule that produced it. It also sets clear limits.

• It will miss mistakes. A comma missing after a long opening clause, a possessive without its apostrophe, or a question that ends in a period all depend on meaning. A rule cannot see meaning.
• Suggestions need your judgment. They are worded as “Possible …” because the checker has found a pattern that is often wrong, not one that is always wrong.
• It checks punctuation, not grammar or spelling. A sentence can be perfectly punctuated and still say the wrong thing.

Tips for cleaner punctuation

• Do not place commas by ear. “Put a comma where you would pause” produces comma splices and stray commas between a subject and its verb. Ask what the comma is doing: separating list items, setting off an opener or an aside, or joining two sentences with and or but. Our comma cheat sheet lists the jobs on one page.
• Choose one style and keep it. American or British quotation style, Oxford comma or not, em dash or en dash: readers notice a switch more than they notice the choice.
• Clean pasted text first. Text copied from a PDF often has a line break in the middle of every sentence. Join the lines with remove line breaks before you check it.
• Check headings and sentence length too. Headings take no period and follow their own capital rules, which the title capitalization tool applies. Heavy punctuation is often a sign of sentences that try to do too much: the sentence counter shows your longest ones, and the word counter gives you the totals.

All our comma guides

Most comma questions are about one particular word. Linguaholic has a guide for each of the words below, with the rule, the exceptions and example sentences. When the checker flags one of these words, the finding links to its guide.

Comma rules by situation, and other marks

• Comma cheat sheet
• Common comma mistakes
• Unnecessary commas
• Commas with and, but, or, so (FANBOYS)
• Comma before and in a list
• Commas with quotation marks
• Comma after a quotation
• Comma before a name you address
• Comma before subordinate clauses
• Commas before relative pronouns
• Comma before a relative clause
• Commas in addresses
• Comma after a city and a state
• Comma after salutations
• Comma before or after names
• Comma after abbreviations
• Comma before a gerund
• Comma before a verb
• Commas with brackets
• How to use semicolons
• How to use colons
• The history of punctuation marks