Of all the Latin abbreviations that survived into modern business writing, i.e. and e.g. cause the most confusion. They look similar, they both appear inside parentheses, and they both signal a clarification of some kind. But they don't mean the same thing. Using one where the other belongs changes the meaning of your sentence, sometimes dramatically.
What i.e. means
i.e. is short for the Latin id est, which translates as "that is." Use i.e. when you're about to restate or clarify something you've already said. The information after i.e. isn't an example. It's a precise restatement or explanation.
Think of i.e. as equivalent to "in other words" or "to be specific." What follows it exhausts the category. Nothing is left out.
- "The project is due at the end of Q3 (i.e., 30 September)."
- "Please send the report to the decision-maker (i.e., the CFO)."
- "We need the final version (i.e., with all revisions incorporated)."
In each of these, the parenthetical doesn't add examples. It pins down exactly what was meant. There's one answer, and i.e. delivers it.
What e.g. means
e.g. is short for the Latin exempli gratia, which translates as "for the sake of example" or simply "for example." Use e.g. when you're giving one or more examples from a larger set. The list after e.g. is illustrative, not exhaustive.
Think of e.g. as equivalent to "for example" or "such as." Readers understand that other items in the same category exist, even if you haven't listed them.
- "Please bring the relevant documents (e.g., your passport, proof of address, or a utility bill)."
- "Consider adding visual aids (e.g., charts or tables) to the report."
- "The proposal should address key risks (e.g., budget overrun, timeline slippage)."
In each of these, the parenthetical gives a sample. Other examples could easily appear. The writer is not claiming the list is complete.
A quick test to tell them apart
Before you type either abbreviation, ask yourself one question: is what follows a complete definition or a partial list?
Complete definition or restatement: use i.e. Partial list of examples: use e.g.
Another useful trick is substitution. Replace the abbreviation with plain English and read the sentence out loud. If "that is" fits, you want i.e. If "for example" fits, you want e.g. If neither fits cleanly, rewrite the sentence rather than guessing at the abbreviation.
Punctuation: the periods and the comma
Both abbreviations carry two periods: i.e. and e.g. That's non-negotiable in formal writing. Dropping them to ie or eg is increasingly common in casual digital communication, but it looks sloppy in professional documents, reports, and business correspondence.
A comma follows the abbreviation in American English: "(i.e., the CFO)" and "(e.g., charts or tables)." British English sometimes omits the comma, but the comma version is safe for any audience and is the default in most style guides for business writers. Pick one convention and apply it consistently across a document.
When these abbreviations appear inside parentheses, they don't need an additional punctuation mark before the opening bracket. The sentence structure handles that.
Common mistakes to avoid
The most frequent error is using i.e. when the writer means e.g. This matters because i.e. tells the reader the list is definitive. If you write "the approved formats (i.e., PDF, DOCX, or XLSX)" but there are actually five approved formats, you've misled the reader. Use e.g. to signal that the list is a sample.
The second common mistake is using e.g. and then writing "etc." at the end of the list. E.g. already signals that the list is incomplete. Adding "etc." is redundant. Cut it.
A third issue is placing these abbreviations in running prose when plain English would be cleaner. The abbreviations belong in parenthetical clauses, footnotes, and technical writing. In a standard business email or report sentence, "for example" and "that is" read more naturally and are less likely to confuse international readers. This matters especially when writing for global audiences: not every reader is equally comfortable with Latin abbreviations, and plain English alternatives remove ambiguity entirely. Writers working across international teams will find this discussed in more depth in this guide to plain English for international readers.
i.e. vs e.g. at a glance
Here's a direct comparison to keep nearby when you're editing:
| Abbreviation | Stands for | Means | Use when |
|---|---|---|---|
| i.e. | id est | "that is" | Restating or defining something precisely |
| e.g. | exempli gratia | "for example" | Giving one or more examples from a larger set |
Should you even use them?
Both abbreviations are standard in formal writing and widely understood in professional contexts. That said, some style guides, including the GOV.UK style guide, recommend writing out "that is" and "for example" in full to improve accessibility and readability, particularly for readers whose first language isn't English.
The honest answer is: use them when precision matters and your audience is comfortable with them. In formal contracts, technical documents, and academic-style reports, i.e. and e.g. are perfectly appropriate. In short business emails or communications aimed at mixed-language audiences, plain English is the safer bet. The abbreviations themselves aren't the problem. Misusing them, or scattering them through prose where they don't belong, is.
Getting these two right is a small thing. But small things accumulate. A writer who uses i.e. and e.g. correctly signals attention to detail, and that credibility carries through to everything else they write. It's the same instinct that prompts careful writers to double-check affect vs effect before they hit send.