The Comma
59 rules
Comma Between Independent Clauses Joined by a Coordinating Conjunction
Use a comma to separate independent clauses in a compound sentence when they are joined by a coordinating conjunction (and, but, or, nor). If both clauses are short (roughly five words or fewer), the comma may be omitted. When a dependent clause at the beginning of the sentence equally governs both independent clauses joined by 'and' or 'or,' do not use a comma between them. However, if the conjunction is 'but,' the comma may still be needed because 'but' often signals that the dependent clause no longer governs equally.
Comma to Separate Items in a Series
Use a comma to separate words, phrases, or clauses in a series. Court reporters should use the serial comma — also called the Oxford comma — (the comma before 'and' at the end of the series) for exactness. However, if the last two items belong together as a unit, omitting the final comma can show this. A series of short independent clauses may be separated by commas, but if clauses are long or legally complicated, semicolons or periods are better. When a series contains items that themselves have commas, use semicolons to separate the items.
No Commas When Conjunctions Separate Every Item in a Series
When conjunctions (and, or, nor) appear between every item in a series, do not use any commas. The conjunctions themselves provide the separation.
Commas in Firm or Company Names
When a series appears within the name of a firm or company, commas may or may not separate the individual names. Firms usually omit the comma before 'and' (or the ampersand). Follow the company's own preference if possible.
Comma Between Coordinate (Equal-Rank) Adjectives
Use a comma to separate adjectives of equal rank that precede the noun they describe. Two tests determine if adjectives are coordinate: (1) Can you insert 'and' between them without changing the meaning? (2) Can you reverse their order naturally? If both tests pass, use a comma. If not, the adjectives are not coordinate and no comma is needed.
Commas Around Adjectives That Follow the Noun
When adjectives follow the noun they describe instead of preceding it, use a pair of commas to set them off if they appear in the middle of the sentence. If they appear at the end of the sentence, use a single comma to separate them from the noun.
Comma with Nouns of Direct Address
Use a comma to separate the name or title of the person being spoken to (noun of direct address) from the rest of the sentence. If the name is at the beginning or end, use one comma. If it falls in the middle, use a pair of commas. The speaker's inflection can change the meaning — a comma placement can determine whether a name is being addressed or being discussed.
Comma to Separate a Direct Quotation
Use a comma (or a pair of commas) to separate a direct quotation from the rest of the sentence. The comma is always placed inside the closing quotation mark. When words are used to replace punctuation or indicate pronunciation, set them off with commas.
Commas in Dates and Addresses
In dates, use a comma after the day of the month and after the year when the date appears mid-sentence. If only the month and year are given, commas may be used or omitted. In military-style dates (12 September), no commas are used. In addresses, use a comma after each element (street, city, state) but not between the state and ZIP Code. Do place a comma after the ZIP Code if the sentence continues.
Commas with Titles, Degrees, and Designations After Names
Use a pair of commas to set off titles, academic degrees, and corporate designations (CEO, Esq., Ph.D., Inc., Ltd., Jr., Sr.) that follow personal names or company names. When Jr., Sr., or a numerical designation follows a name, the commas may be omitted per individual or company preference. In the possessive form, use only the first comma. When 'senior' or 'junior' distinguishes a father from a son, either the word or abbreviation is acceptable.
Commas Around 'Etc.' in a Series
Use commas around 'etc.' when it appears within a sentence at the end of a series. A comma precedes and follows it (unless it ends the sentence, in which case the period in 'etc.' serves as the sentence-ending period). Court reporters need not spell out 'et cetera' unless it is the only word on the line.
Commas to Separate Numbered References (Sections, Pages, Verses)
Use commas to separate numbered references to sections, pages, verses, and acts when they appear in running text.
Comma with Spelled-Out Enumerations (First, Second, Third)
Use a comma to introduce the first spelled-out enumeration after the verb, and a comma after all subsequent spelled-out enumerations in the same sentence. The enumeration word is followed by a comma, and a semicolon separates each enumerated item.
Comma with 'Please,' 'Too,' and 'Also'
Use a comma to set off 'please' when it is the last word of a sentence but not the last word of a dependent clause or phrase. If 'please' falls mid-sentence as an interrupter, set it off with commas. For 'too' and 'also' at the end of a sentence, the trend is to omit the comma, though commas are placed around 'too' when it separates the subject from the verb.
Comma in Numbers (Thousands Separator)
Use a comma in numbers of four or more digits to separate hundreds, thousands, millions, and billions. Do not use commas in numbers that represent house addresses, page numbers, policy numbers, social security numbers, street numbers, telephone numbers, years, or ZIP Codes. Patent and serial numbers from the U.S. Patent Office do retain commas. If a number is verbalized in even hundreds, it may be written without a comma.
Comma After Introductory Adverbs and Transitional Words
Use a comma after an introductory adverb or transitional word at the beginning of a sentence (e.g., accordingly, actually, however, moreover, fortunately, frankly, naturally, obviously, etc.). These words often act as transitions between sentences or express the speaker's independent view. Do not set off 'hence,' 'thus,' 'so,' or 'yet' with a comma. For 'now' and 'then,' use a comma only if they are used conversationally (like 'well' or 'so') — not if they express time or sequence.
Comma with Introductory Exclamations (Well, Oh, Why, Alas, My)
Use a comma to set off 'well,' 'why,' 'oh,' 'alas,' 'my,' and similar mild exclamations when they are used as introductory words. Use a pair of commas when they interrupt the flow mid-sentence. For courtroom transcripts, do not use exclamation points. Use a period (not a comma) to separate 'okay' and 'all right' when they are spoken as acknowledgments of a previous response.
Comma After 'Yes' or 'No' at the Beginning of a Sentence
Use a comma after 'yes' or 'no' at the beginning of a sentence when the statement that follows confirms or restates the yes/no. If the statement that follows explains or adds to the response, use a period after 'yes' or 'no' instead.
Comma After a Long Introductory Prepositional Phrase
Use a comma after a long introductory prepositional phrase (four or more words). Short, specific prepositional phrases at the beginning of a sentence generally do not need a comma. However, some short general or transitional prepositional phrases (e.g., 'in fact,' 'by contrast,' 'as a rule,' 'of course,' 'in any case') are set off because they contrast, restate, illustrate, or affirm.
Comma After an Introductory Participial Phrase
Use a comma to set off an introductory participial phrase regardless of its length. A participle is a verb form used as an adjective that describes a noun or pronoun in the sentence.
Comma After an Introductory Infinitive Phrase
Use a comma to set off an introductory infinitive phrase regardless of its length. An infinitive phrase is a verb preceded by 'to.'
Comma After an Introductory Adverb Clause
Use a comma after an introductory adverb clause regardless of its length. The comma is placed where the dependent clause ends and the independent clause begins. Adverbs that commonly begin introductory clauses include after, although, as, because, if, since, when, and where. Expressions like 'Just so I'm clear' may be treated as introductory clauses (comma) or as shortened prefaces (colon), depending on inflection and delivery.
Comma Before a Nonessential Adverbial Clause
Use a comma before a nonessential adverbial clause — one that follows the main clause and adds description or explanation but is not required for the sentence's core meaning. Words and phrases that always introduce nonessential clauses include: although, among which, even though, for, no matter what/who/which, none of which/whom, some of which/whom, though, and whereas. If the adverbial clause explains or elaborates (nonessential), a comma precedes it. If it states why (essential), no comma.
No Comma Before an Essential Adverbial Clause
Do not use a comma before an adverbial clause that is essential to the meaning of the sentence. The clause is necessary — removing it would change the core meaning. Adverbs that frequently introduce essential clauses include as, because, if, since, so (purpose), and unless. The same word can introduce essential or nonessential clauses depending on context.
Commas with Appositives
Use commas to set off appositives — nouns or noun phrases placed after another noun to rename or explain it. If the proper noun comes first, the appositive description that follows is nonessential and set off with commas. If a common noun comes first with a superlative or qualifying adjective (best, latest, first, last, only), and is then followed by a proper noun that identifies it, the proper noun is essential (restrictive) and is not set off with commas. Reflexive pronouns (myself, yourself, himself) may or may not be set off, depending on whether emphasis or clarity is needed.
Commas with Appositives Introduced by 'Especially,' 'Or,' or 'Particularly'
Use commas before or around appositives introduced by 'especially,' 'or,' or 'particularly.'
Comma After a Proper Name Followed by a Long Renaming Prepositional Phrase
When a proper name is followed by a long prepositional phrase that renames or identifies the person, use a comma (or commas) to set off the phrase. If the phrase is short, no commas are needed.
Comma with a Nonessential Participial Phrase
Use a comma or commas to set off a nonessential (nonrestrictive) participial phrase. If the participial phrase comes at the end of the sentence but refers to the subject, use a comma to separate it from the rest of the sentence.
Comma with 'Who,' 'Which,' 'Whom,' and 'In Which' Clauses
Use a comma or commas to set off a dependent clause beginning with 'who,' 'which,' 'whom,' or 'in which' when the clause renames and the renaming is unnecessary to the sentence's core meaning (nonrestrictive). These clauses add extra information but could be removed without changing the essential meaning.
Comma with 'Together With,' 'As Well As,' 'Accompanied By,' etc.
When a phrase introduced by 'accompanied by,' 'along with,' 'as well as,' 'besides,' 'in addition to,' 'plus,' or 'together with' comes between the subject and the verb, set the entire phrase off with commas. If the phrase occurs elsewhere in the sentence, the commas may be omitted.
Comma with 'Such As' or 'Like'
When 'such as' or 'like' introduces a required or necessary explanation or example, do not use a comma before it. When the explanation is unnecessary (the sentence would be complete without it), use a comma before it.
Commas with Parenthetical Expressions
Use commas to set off parenthetical expressions — words, phrases, or clauses that interrupt the smooth flow of the sentence or that come at the end. Common examples include 'I believe,' 'if any,' 'in effect,' 'in fact,' 'as a matter of fact,' 'if I remember correctly,' 'to tell you the truth,' 'from the moment I met him,' etc. When a parenthetical expression precedes the conjunction in a compound sentence, keep the comma before the conjunction and add one after the parenthetical expression.
Comma with Contrasting Expressions (Even Though, Never, Rather, Though Not)
Use a comma to set off contrasting expressions introduced by 'even though,' 'never,' 'rather,' 'though,' 'though not,' 'not,' or similar words. If 'rather than' comes at the end of the sentence, no comma is necessary.
Comma Between Identical or Repeated Words
Use a comma to separate identical words that appear next to each other if they cause confusion or rereading. If an adjective or adverb is repeated for emphasis, use a comma to separate the pair. Also use a comma between non-identical but similar words that could cause misreading. Some common repetitions (e.g., 'that that,' 'had had') are so familiar they do not need a comma. For clarity, a comma between identical words may be necessary even if it separates a subject from its verb.
Comma Between Two Proper Nouns to Prevent Confusion
Use a comma to separate two proper nouns that appear next to each other if they could cause confusion or misreading.
Comma Between Two Sets of Figures
Use a comma to separate two sets of figures that appear next to each other if they could cause confusion or misreading.
Comma to Separate a Statement from an Echo/Tag Question
Use a comma to separate a statement from an echo (tag) question when the subjects and verbs are the same in both clauses. The whole sentence ends with a question mark.
Comma When the Verb Is Omitted in a Compound Sentence
Use a comma to mark the spot where a verb has been omitted from a compound sentence when the idea is readily understood without it. The comma shows the reader where the missing verb would be. The comma of omission replaces the missing coordinate conjunction in compound dependent constructions.
Comma When 'Of the' or 'As' Is Omitted
Use a comma when words like 'of the' or 'as' are missing from a sentence but are easily understood. The comma signals the omitted word and prevents misreading.
Comma with Filler Words (You Know, I Mean, Like, Okay, See)
Use commas to set off filler words and expressions that speakers use to fill gaps when they are unsure, seeking approval, or speaking habitually. Common fillers include 'you know,' 'you understand,' 'I mean,' 'okay,' 'see,' 'say,' and 'like.' However, when 'like' is used as a synonym for 'about' or 'around' (approximation), it is not a filler and should not be set off with commas.
Comma After a Mild One-Word or Two-Word Command
Use a comma to set off a mild one-word or two-word command (like 'Look,' 'Remember,' 'Mind you,' 'See') when it is followed by a complete sentence.
No Comma After a One-Word Command When It Flows into the Sentence
If a complete sentence follows a one-word command but there is no natural pause or separation between them, do not use a comma. The command word flows directly into the rest of the sentence as part of its grammatical structure.
Comma with 'Not Only…But Also'
In a 'not only…but (also)' construction, use a comma before 'but' or 'but also' when both the 'not only' beginning and the 'but/but also' ending are full clauses. If either the 'not only' part or the 'but also' part is only a word or a phrase (not a full clause), do not use a comma.
Comma May Be Omitted Between Short, Parallel Independent Clauses
When a coordinate conjunction is linking two independent clauses that are very short and very parallel, the comma before the conjunction may be omitted if you choose. This is a 'may omit' rule — the comma is not wrong when there is an independent subject and verb after a coordinate conjunction. Two conditions must be met: the construction must be parallel, and both sentences must be short (roughly four words or fewer in each). It is not acceptable to omit the comma just because one sentence is short — both must be short.
Comma Before Conjunction Linking Two Command-Form Sentences
When a coordinate conjunction links two sentences that both use the command form — where the subject 'you' is assumed — use a comma before the conjunction. If both command sentences are short, the comma may be omitted. Some experts believe the assumed 'you' applies only to the first verb and that the conjunction simply links two verbs, making the comma unnecessary. As always, be consistent.
No Comma Before Conjunction When Clauses Share a Common Element
When there are two sets of subjects and verbs that share a common element after the second set, do not use a comma before the coordinate conjunction even though you have an independent subject and verb after it. The shared element (a direct object, noun clause, infinitive phrase, or other completer) serves both verbs, meaning the second clause is not truly independent. Be on the lookout for this — once you are accustomed to always putting the comma for subject and verb after the conjunction, this exception is easy to miss.
No Omission Comma When Parallel Sentences Are Joined by a Conjunction
When two parallel sentences are joined by a coordinate conjunction, do not use a comma before the conjunction (because there is no independent subject and verb in the second part), and do not use a comma of omission for elements present in the first sentence but absent from the second. The comma of omission applies only when parallel clauses are joined by a semicolon without a conjunction — not when a conjunction links them.
Comma Between Identical Repeating Words
Use a comma to separate two identical words that appear next to each other and serve exactly the same grammatical function. This does not apply when the two identical words serve different functions — for example, when one is a relative pronoun and the other is demonstrative, or when one is an auxiliary verb and the other is the main verb. When repeated words create a double-verb situation, a comma between them is optional — use your judgment based on readability.
Comma in 'The More...The Better' and Similar Comparative Patterns
Use a comma to separate the two elements in idiomatic comparative constructions that follow the pattern 'the more...the less,' 'the bigger...the better,' 'the farther...the fewer,' and similar expressions. This construction always contains comparison forms and always takes a comma.
Comma with a Nominative Absolute
Use a comma to separate a nominative absolute from the rest of the sentence. A nominative absolute is a noun or pronoun followed by a participle that is not grammatically related to the sentence content. It has the feel of an adverb but is grammatically independent from the sentence. When the nominative absolute is in the middle of the sentence, it is surrounded with commas.
Comma with Throwaway Words (Like, You Know, Now, Then)
Use a comma after a throwaway word at the beginning of the sentence and before a throwaway word at the end. A throwaway is a word used parenthetically that has no real meaning in the sentence. Common throwaways include 'like,' 'you know,' 'now,' and 'then.' Note that 'now' and 'then' are only throwaways when they carry no adverbial meaning — when they mean 'at this time' or 'at that time,' they are adverbs and take no punctuation. When a throwaway is in the middle of the sentence, it is surrounded with commas.
Comma with a Number or Letter Used to Denote a List Item
When a number or letter is used parenthetically to delineate items in a series, use a comma after it at the beginning of the sentence and before it at the end. Words like 'first,' 'firstly,' 'last,' and 'then' used to denote items in a listing follow this same rule. When the number or letter is in the middle of the sentence, it is surrounded with commas.
Comma with a Neutral Remark (In My Opinion, Frankly, Obviously)
Use a comma after a neutral remark at the beginning of the sentence and before a neutral remark at the end. A neutral remark imposes the speaker's viewpoint on the sentence and has nothing to do with the sentence content. Common neutral remarks include phrases like 'in my opinion,' 'to your knowledge,' 'as you see it,' 'off the top of my head,' and single words like 'clearly,' 'obviously,' and 'frankly.' When a neutral remark is in the middle of the sentence, it is surrounded with commas.
No Comma for Short Introductory Words or Word Groups Acting as Simple Modifiers
Do not use punctuation for a single word or short word group at the beginning of a sentence that acts as a simple modifier, usually adverbial. Use a comma for long word groups — the cutoff is generally four or five words — that act as simple modifiers at the beginning of a sentence. These rules apply to simple modifiers only, not parentheticals, neutral remarks, or clauses.
Comma After an Objective Case Noun Clause Pulled to the Beginning of a Sentence
Use a comma after an objective case noun clause that has been pulled out of its natural word order to the beginning of the sentence. A noun clause that is the subject of the sentence is NOT out of order and does not take punctuation — it is in its natural position.
Introductory Element Comma Rules Apply Regardless of a Leading Coordinate Conjunction
If an introductory element does not need a comma after it at the beginning of a sentence, do not add one just because the sentence starts with a coordinate conjunction. If an element does need a comma after it, still use the comma when the sentence begins with a coordinate conjunction. Elements that always require surrounding commas (direct address, parentheticals, interjections) should be surrounded after the coordinate conjunction as well.
Comma for Clarity to Prevent Misreading
Use a comma any time it will prevent a misreading or add clarity to a sentence, even when no specific comma rule requires one. This comma can be inserted anywhere the context calls for it. Use this freedom judiciously — do not overuse it.
No Comma Between Subject and Verb, Verb and Object, or Verbal and Completer
Do not place a single separating comma between the subject and its verb, between a verb and its direct object, or between a verbal (an -ing, -ed, or to form) and the word that completes it. This error most commonly occurs in long, complex sentences where the distance between these elements tempts the writer to insert a comma. The grammatical connection between these pairs must not be broken by a single comma — though a pair of commas setting off a parenthetical element between them is acceptable.
No Comma in a Compound Dependent Construction
When a coordinate conjunction (and, but, or, nor) joins elements that cannot stand alone as complete sentences — such as two verbs sharing the same subject, two prepositional phrases, two dependent clauses, or two completer words — do not use a comma before the conjunction. A comma before the conjunction is only correct when both sides are independent clauses (each with its own subject and verb forming a complete thought).