How to Use Abbreviations in Formal Writing (2024)

Here are the generally accepted guidelines for using abbreviations in formal texts:

1. Abbreviate a term only if doing so improves clarity and readability.
2. Provide the full form of an abbreviation at first use.
3. Avoid starting a sentence with an abbreviation.
4. Use all capital letters for initialisms and acronyms (USA, UK, EU, CEO, GPS) except abbreviated Latin terms (e.g., i.e., etc., p.m.) and scientific and technical abbreviations (ppm, mph, ml, kg). Capitalize contractions of titles and proper nouns (Mr., Dr., Rev., Gen., Jan.).
5. Don’t use periods in abbreviations with two or more capital letters (except scientific abbreviations and abbreviated SI units).
6. Form the plural of an abbreviation by adding s or es without an apostrophe (DVDs, CMSes, Drs. Who and Strange).
7. Use a or an before an abbreviation depending on how it is pronounced (a US senator, an ATM, an MBA degree)

We discuss these and certain exceptions in detail below, with examples.

When to abbreviate a term

An abbreviation as we know is the shortened form of a term. It is usually formed using the first letters of the words of a multi-word term, but it may simply be the short form of a single word. Abbreviations can help you avoid repeating long phrases in a document, thus making it more easily scannable and readable. But abbreviate a term only if it appears multiple times in a text (at least three to five times, depending on the length of the document).

Also use abbreviations for terms that are known better by their abbreviated rather than full forms—for example, PDF, HTML, ATM, CEO.

When to avoid abbreviations

Abbreviations can be quite useful when space is limited, but you should confine the use of nonstandard abbreviations to tables, graphs, and figures, except in scientific and technical writing.

Avoid using nonstandard abbreviations in headings; you want the reader to be able to easily skim the document or just its table of contents. Also avoid using abbreviations in captions of figures and tables, which are considered reproducible in other texts and thus standalone.

Providing the full form

In general, explain an abbreviation by providing its full form at first use in a document.

Don’t capitalize the words in the full form of an abbreviation unless it is a proper noun.

If a term usually appears in its abbreviated rather than complete form, the abbreviation need not be explained: for example, USA, MBA, PhD, PDF, BC/AD, BCE/CE, FAQ, URL, Mr., Dr., rpm, i.e.

You also don’t need to provide the full form of an abbreviation listed as a noun rather than an abbreviation in standard dictionaries like Merriam-Webster. Such terms that are now known better by their abbreviated forms include DNA, IQ, URL, HTML, PDF, hi-fi, TV, and (unfortunately) COVID.

Use of capital letters

Abbreviations that are formed using the initial letters of the words of a term (initialisms or acronyms) generally comprise all capital letters.

Contractions usually appear in lowercase letters, but those that appear before a name as titles or are part of a proper noun are capitalized (the first letter of the contraction is then a capital letter).

Technical and scientific abbreviations comprising the initial letters of a term may contain lowercase letters. Abbreviated units of measurement are also not capitalized.

Latin abbreviations are also generally lowercased.

Use of periods

In general, abbreviations with at least two capital letters contain no period.

Abbreviations that end in lowercase letters often contain periods.

However, periods are omitted in scientific and technical abbreviations, abbreviated SI units, and abbreviations containing the preposition per.

Contractions and other shortened forms that end in a lowercase letter usually take a period.

Use of a/an and the

Use a or an before an abbreviation depending upon how it is pronounced. If it starts with a consonant sound, use a; otherwise, use an.

With acronyms (abbreviations pronounced as words), the article the is omitted, even when it would be used with the full form.

But with initialisms (in which the individual letters are pronounced), use the with the abbreviation if it is used with the full form.

At the start of a sentence

In formal writing, avoid starting a sentence with an abbreviation. Use the full form instead, or rephrase.

Because acronyms and contractions are read aloud as words, they are acceptable at the beginning of a sentence.

If using the full form makes the sentence awkward, use the abbreviated form—for example, to refer to company names.

Plural forms

To form the plural of an abbreviation, simply add s (an apostrophe is unnecessary).

Abbreviations that already end in S can be pluralized either by adding another s or by adding es.

To form the plural of a contraction, add s and place a period after.