How to Abbreviate: Abbreviation Rules and Examples

What is an abbreviation?

Any shortened written form counts. If you write "Sat." on a calendar or "Apt. 4B" on an envelope, you have used one. The full word is still what the reader "hears" in their head: most people read "Sat." as Saturday, not as "sat."

That is the real abbreviation meaning in everyday use: a shortcut on paper that stands in for something longer. A good one is short, but it is also clear. If a reader has to stop and guess, the space you saved was not worth it.

To find what the right short form is for a word, look for a standard abbreviation first. Many words already have one that style guides, the Postal Service and recipe writers agree on.

Five kinds of abbreviations

Initialisms and acronyms are special kinds of abbreviations built from first letters. For how those two are told apart, read what is an acronym.

How to abbreviate a word in four steps

1. Check for a standard form. Many words already have one. Appointment is appt., department is dept., boulevard is Blvd. Use these instead of making up your own.
2. If none exists, keep the beginning. The first syllable or two usually carries the word: "approximately" becomes approx., "miscellaneous" becomes misc.
3. Or keep the key consonants. Dropping vowels often works for longer words: building becomes bldg., management becomes mgmt.
4. Test it on a reader. If a coworker cannot tell what it means, spell the word out or explain it the first time.

Periods, capitals and plurals

American English and British English handle periods a little differently, and this is where most questions come from.

• Periods: in the US, shortened words and titles usually take a period: Mr., Dr., Jan., St. British writers often drop it on contractions, writing Mr and Dr.
• First letters: initialisms and acronyms are usually written without periods today: FBI, NASA, DVD. Some still carry dots out of tradition, for example U.S. in many newspapers and a.m. or p.m. in times.
• Capitals: keep the capital if the full word has one. Monday becomes Mon., but "approximately" stays lowercase as approx.
• Plurals: add a lowercase s with no apostrophe: appts., IDs, PDFs. Units of measure do not change: 1 lb and 5 lb, 1 oz and 8 oz.
• A or an: go by the sound, not the letter. "An FAQ" (eff), "a NASA mission," "an hr." (hour).

Where you see abbreviations most

Each setting has its own set of short forms, and readers in that setting expect them.

• Addresses: St., Ave., Blvd., Apt. and Ste., plus two-letter state codes from the state abbreviations list.
• Recipes: tbsp, tsp, c. and oz.
• Calendars and planners: month abbreviations such as Sept. and Dec., days like Wed. and Thu., and appt.
• Forms: DOB for date of birth, Attn. for the person a letter should reach, N/A for not applicable.
• Writing in general: i.e. and e.g., plus etc.

What abbreviation should you use for common words?

For a longer list grouped by topic, see the common abbreviations section.

When to spell the word out instead

Short forms are not always the polite choice. Spell the word out when:

• the writing is formal, such as a cover letter, an essay or a wedding invitation;
• the reader may not know the short form, for example a customer or a new employee;
• the word starts a sentence, where "Approximately" reads better than "Approx.";
• two meanings are possible, as with "St." for both street and saint.

A safe habit for reports and articles: write the full term the first time, put the short form in parentheses, then use the short form after that. "The Parent Teacher Association (PTA) meets Tuesday. The PTA will vote on the budget."

Abbreviation or acronym?

Every acronym is an abbreviation, but not every abbreviation is an acronym. "Dept." is an abbreviation you never say out loud; you read it as department. NASA is an acronym you say as a word. FBI sits in between as an initialism, said letter by letter. For side by side examples, read acronym vs abbreviation.