When should I use "I am writing to inform you" vs "Just letting you know" in emails?
I'm writing an email to my professor and I'm unsure about the right tone to use. For example, should I start with, "I am writing to inform you that I will be absent next week," or is it okay to say, "Just letting you know I can't make it next week"?
I always get confused about when it's better to use more formal language versus when an informal style is acceptable. Are there specific situations where one is preferred over the other? I'd really appreciate any advice or examples you can share!
Context:
Academic emails to university professors (US, college setting)
What to Know
| Question You Likely Still Have | Direct Answer | How To Apply It |
|---|---|---|
| What is the core rule for "i am writing to inform you" vs "just letting you know" in emails? | Examples: Formal: "I am writing to inform you that I will be absent from class on Monday, June 10th, due to a medical appointment." Informal: "Just letting you know I can't make i… | For more casual contexts—such as updating a classmate about group work—informal patterns like "Just letting you know..." or "FYI, I..." are fine, but these are too casual for prof… |
| How do I apply "i am writing to inform you" vs "just letting you know" in emails in a sentence like mine? | For more casual contexts—such as updating a classmate about group work—informal patterns like "Just letting you know..." or "FYI, I..." are fine, but these are too casual for prof… | For formal situations—such as informing your professor of an absence, a deadline issue, or any official matter—structured, impersonal openings like "I am writing to inform you tha… |
| What mistakes should I avoid with "i am writing to inform you" vs "just letting you know" in emails? | For formal situations—such as informing your professor of an absence, a deadline issue, or any official matter—structured, impersonal openings like "I am writing to inform you tha… | In academic email writing, especially to professors, it's useful to identify reusable patterns for choosing your tone. |
3 Answers
In academic email writing, especially to professors, it's useful to identify reusable patterns for choosing your tone. For formal situations—such as informing your professor of an absence, a deadline issue, or any official matter—structured, impersonal openings like "I am writing to inform you that..." or "I would like to inform you..." are preferred. These convey respect and professionalism.
For more casual contexts—such as updating a classmate about group work—informal patterns like "Just letting you know..." or "FYI, I..." are fine, but these are too casual for professor correspondence.
Examples:
- Formal: "I am writing to inform you that I will be absent from class on Monday, June 10th, due to a medical appointment."
- Informal: "Just letting you know I can't make it to the study group next week."
Practice: Try drafting a message to your professor using the formal pattern. Look for any casual phrases you might use in daily conversation and edit them out. Ask yourself: Does my opening show respect and clarity?
Self-check: If your message is going to someone in authority or about an official issue, use the more formal opening; reserve informal phrases for peers.
When deciding between formal and informal phrases, compare near-identical sentences to see how they change the tone of your email. Academic emails to professors usually require a more formal approach, which demonstrates respect and clarity.
Example 1 (Formal): "I would like to let you know that I will be unable to attend class next Wednesday due to a prior commitment."
Example 2 (Informal): "Just letting you know I can't be in class next Wednesday."
Notice that the formal version uses more complete sentences and polite structure. The informal example is direct but may come across as too casual for professor correspondence.
Practice: Write two versions of your message—one formal and one informal—then read them aloud. Which sounds more appropriate for a professor?
Correction tip: If your sentence uses contractions (like "can't"), or leaves out a subject, it's probably too informal for academic contexts.
A helpful method for choosing between formal and informal email language is to check your sentences for tone markers. Ask yourself if your sentence could be used in a conversation with a friend—if so, it may be too informal for professors.
Example Formal: "This email is to notify you that I will not be able to attend class on Friday, June 14th."
Example Informal: "Hey, just wanted to let you know I’ll miss class Friday."
Try this: Take a recent draft to a professor and underline casual words (like "hey," "just," or contractions). Rewrite the sentence to replace them with more formal alternatives (like "notify" instead of "let you know").
Self-check: When you re-read your message, does it read as respectful and professional? If not, adjust with more formal patterns.
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