Note: This page reflects APA 6, which is now out of date. It will remain online until 2021, but will not be updated. The equivalent APA 7 page can be found here.

In APA, abbreviations should be limited to instances when a) the abbreviation is standard and will not interfere with the reader’s understanding and b) if space and repetition can be greatly avoided through abbreviation.

There are a few common trends in abbreviating that you should follow when using APA, though there are always exceptions to these rules. When abbreviating a term, use the full term the first time you use it, followed immediately by the abbreviation in parentheses.

According to the American Psychological Association (APA), abbreviations are best used only when they allow for clear communication with the audience.

Exceptions: Standard abbreviations like units of measurement and states do not need to be written out. APA also allows abbreviations that appear as words in Merriam-Webster’s Collegiate Dictionary to be used without explanation (IQ, AIDS, DNA, FBI).

Do not use periods or spaces in abbreviations of all capital letters, unless it is a proper name or refers to participants using identity-concealing labels: 

Exceptions: Use a period when abbreviating the United States as an adjective (U.S. Marines or U.S. Senator)

Use a period if the abbreviation is a Latin abbreviation or a reference abbreviation:

Do not use periods when abbreviating measurements:

Exceptions: Use a period when abbreviating inch (in.) to avoid confusion.

Units of measurement and statistical abbreviations should only be abbreviated when accompanied by numerical values:

Only certain units of time should be abbreviated.

Do not abbreviate:

Do abbreviate:

To form the plural of abbreviations, add s alone without apostrophe or italicization.

Exception: Do not add s to pluralize units of measurement (12 m not 12 ms).

Abbreviations in Citations

Citations should be as condensed as possible, so you should know the basic rules of abbreviation endorsed by the APA to provide your readers with reference information.

Always abbreviate the first and middle names of authors, editors, etc.

Use the following abbreviations within citations (take note of capitalization):