How to Use 'E.g.' and 'I.e.'
The terms e.g. and i.e. mean different things, and it is important to use the correct abbreviation to ensure that the meaning of a sentence is retained.
Sarah Mudrak, PhD
PhD, Genetics
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There are a few Latin terms that are still commonly used in English scholarly writing, including the abbreviations 'e.g.' and 'i.e.' Sometimes writers use these abbreviations interchangeably, but these terms mean different things, and it is important to use the correct abbreviation to ensure that the meaning of a sentence is retained. Both of these abbreviations are commonly used at the beginning of nonrestrictive elements that are enclosed in either commas or parentheses. Most style guides suggest the use of a comma after both e.g. and i.e.
E.g. Meaning (exempli gratia)
e.g. is the abbreviation for the Latin phrase exempli gratia, meaning "for example." This abbreviation is typically used to introduce one or more examples of something mentioned previously in the sentence and can be used interchangeably with "for example" or "such as." The use of e.g. implies that there are other examples not mentioned in the list. Here are some examples of how to use e.g. in a sentence:
"The Summer Olympics is composed of a variety of sports (e.g., gymnastics, swimming, and tennis)."
"Many genes are involved in neural tube development, e.g., Sonic Hedgehog, BMPs, and the Hox genes."
Note: because e.g. implies that other examples are being omitted, do not use etc. in the same list.
I.e. Meaning (id est)
i.e. is the abbreviation for the Latin phrase id est, meaning "that is." This abbreviation is used when you want to specify something mentioned previously; it can be used interchangeably with "specifically" or "namely." Here are some examples of how to use i.e. in a sentence:
"Only one city, i.e., London, has hosted the Summer Olympics three times."
"Every genetics student learns the two basic methodologies in the field, i.e., forward genetics and reverse genetics."
Easy Ways to Remember the Difference
A helpful way to remember which abbreviation to use is by looking at the first letter in each acronym and using mnemonic devices. If you're confused about which abbreviation to use, associate the 'i' in i.e. with "in other words." For e.g., think of the 'e' as standing for "example" instead of the less common term "exempli."
I.e. and E.g. Punctuation and Formatting
Parenthesis are not completely necessary, but they help the reader follow and understand the use of the abbreviation.
Always use periods after each letter in both acronyms.
A comma should be used after the acronym like the following:
i.e.,
e.g.,
Don't use italics.
Use lowercase letters when using i.e. or e.g. in a sentence. The only exceptions to this is when:
The abbreviation starts a sentence
The abbreviation is in the title
We hope that this clears up some confusion about these terms. Please email us with any questions. Best of luck with your writing!
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