Should you capitalize the word a in a title or headline? Understanding if (or rather, when) a should be capitalized is not very hard. The different cases are discussed in the following sections.
For title case, several cases have to be distinguished. The first one is obvious: a must be capitalized if it is the first word of the title, and the same applies to an.
A Beautiful Day
An Englishman in New York
If a (or an) is not the first word, and is used as an article, then it must be lowercased. Articles (a, an, and the) are always lowercased in title case according to all title case styles.
About a Boy
The End of an Era
Some dictionaries, for example, Merriam Webster, classify a as a preposition when it has the meaning “for each,” “in each,” or “per,” as for example in “once a week.” However, when using title case, it is not important to distinguish whether a is used as an article or as a preposition, since it is lowercased in each case.
Twice a Day
A is not always used as an article or preposition though; it can also be used as a noun. Think of the A train, vitamin A, exhibit A, Q&A, etc. Naturally, a is not lowercased when used as a noun. Here are a few examples:
Insert Knob A in Hole B
Symphony No. 7 in A Major
How to Become a Straight A Student
Officers Find Knife, Class A Drugs and Cash
While a human immediately recognizes when a is used as a noun, such cases pose a problem to algorithms and converters, which usually strictly lowercase a. The Title Case Converter however handles all these examples correctly.
All style guides except for the APA Publication Manual have the rule to capitalize the last word in a title. There are two possibilities how a could be the last word in a title: 1) It is used as a noun, and must then be capitalized in any style as discussed above:
What You Should Know About Hepatitis A
2) It is used as an article, but the following word is omitted and replaced by an ellipsis. In such a case I would argue to lowercase a even though it is the last word, because there is an implied following word that would be the actual last word.
Once Upon a …
Interestingly, the handling of a in sentence case is almost the same as in title case: a is capitalized when it is the first word of the title or used as a noun, and lowercased else.
There is one exception though: when a refers to the letter, then it can either be lowercased or capitalized—both options are correct.
There is no A in “definitely”
There is no a in “definitely”
Capitalize a if it is the first word of the title or is used as a noun
Do not capitalize a in all other cases
Try out the Title Case Converter, which handles these cases automatically.
Photo: Pearse O’Halloran