i.e. vs e.g.: The Difference and How to Punctuate Them

I.e. and e.g. appear constantly in business writing: in meeting notes, project plans, and long email threads. They look similar, they both come from Latin, and they both introduce extra information in a sentence. But they mean different things, and swapping them can change your message. One quick test fixes the problem for good.

1. What each one means

i.e. stands for the Latin id est, meaning "that is." Merriam-Webster explains that it introduces a word or phrase that restates what was said before, in order to clarify it. Cambridge Dictionary describes it as used before information that makes the meaning of something clearer or shows its true meaning.

e.g. stands for the Latin exempli gratia, meaning "for example." Merriam-Webster says it is used in much the same way as "for example," before an item or list of items. Cambridge's business English entry describes it as used for giving one or more examples.

The practical difference:

• i.e. narrows down. What follows is the complete, exact meaning.
• e.g. opens up. What follows is only a sample, and other items could fit too.

2. The substitution test

Merriam-Webster offers a simple check: replace i.e. with "that is" and e.g. with "for example." If the sentence still makes sense, you used the right one.

Try it:

• "Please send the files in a common format, e.g., PDF or Word." Read it as "for example, PDF or Word." That works: other formats might be fine too.
• "Please send the files in our required format, i.e., PDF." Read it as "that is, PDF." That works: PDF is the only required format.

3. Why the choice matters in work emails

Because i.e. means "that is," it tells the reader the list is complete. Because e.g. means "for example," it tells the reader there are other options. Mixing them up can mislead someone.

Before: The offer is open to senior staff, i.e., managers and directors. If there are other senior roles, such as principal engineers, this wording tells them they are excluded.

After (if the list is complete): The offer is open to senior staff, i.e., managers and directors. After (if these are just examples): The offer is open to senior staff, e.g., managers and directors.

Before: Please use an approved vendor, e.g., the one we signed with last month. If that is the only approved vendor, "for example" is wrong.

After: Please use our approved vendor, i.e., the one we signed with last month.

4. Punctuation in American English

Merriam-Webster notes that both i.e. and e.g. are usually followed by a comma, and that the phrase they introduce is often placed inside parentheses or set off after a comma.

Common patterns:

• Parentheses: "Submit receipts for small expenses (e.g., taxis and meals) by Friday."
• After a comma: "The report is due at the end of the quarter, i.e., September 30."

A few more details:

• Periods: American style writes both with periods: i.e. and e.g. Cambridge notes that British usage also accepts eg without periods. If you write for American readers, keep the periods.
• Lowercase in the middle of a sentence: write i.e. and e.g. in lowercase, as in all of the dictionary examples.

5. When to skip the abbreviation

In a short email to someone outside your company, or to readers who are still learning English, the plain words are often clearer. Cambridge notes that e.g. can be read aloud as "for example," and the same idea works on the page:

• "for example" instead of e.g.
• "that is" or "in other words" instead of i.e.

Save the abbreviations for space-limited places like tables, slide notes, and technical documents, where readers expect them.

6. Quick reference

7. Key takeaways

• i.e. means "that is" and introduces a restatement or a complete list.
• e.g. means "for example" and introduces a sample, leaving room for other items.
• Test your choice by substituting "that is" or "for example" and rereading the sentence.
• In American English, write both with periods and usually follow them with a comma.
• For readers who may not know the abbreviations, write "for example" or "that is" instead.