Formal vs Casual Ways to Say ‘Let me know’
If you want to ask someone to update you or give you information, the phrase “Let me know” works in almost any situation. However, the way you say it can change completely depending on whether you are writing a formal email to a client, chatting with a coworker, or texting a friend. This guide gives you direct, practical alternatives for both formal and casual contexts, so you always sound natural and appropriate.
Quick Answer: Which Version Should You Use?
Use a formal version when you are writing to a boss, a client, a professor, or someone you do not know well. Use a casual version when you are talking to friends, family, or close colleagues in everyday conversation or text. The table below shows the most common choices.
| Context | Formal | Casual |
|---|---|---|
| Requesting a decision | Please advise on your decision. | Just tell me what you decide. |
| Asking for updates | Kindly keep me informed of any changes. | Keep me posted. |
| Asking for questions | Should you have any questions, please do not hesitate to contact me. | Let me know if you have questions. |
| Asking for availability | Please confirm your availability at your earliest convenience. | Tell me when you are free. |
Understanding the Tone Difference
The phrase “Let me know” is neutral, but it can sound too direct or informal in a formal email. In casual conversation, it is perfectly fine. The key is to match the tone to the relationship and the situation. Formal versions often use words like “please,” “kindly,” “advise,” “inform,” and “confirm.” Casual versions use shorter phrases, contractions, and everyday words like “tell,” “say,” “drop,” and “shoot.”
Formal Alternatives to ‘Let Me Know’
Use these in professional emails, official letters, or when speaking to someone in a position of authority. They show respect and professionalism.
1. Please advise
This is a standard formal phrase used in business writing. It is especially common when you need a decision or recommendation.
Example: “Please advise on the next steps for the project.”
2. Kindly inform me
This is more polite and slightly old-fashioned. It works well in very formal correspondence.
Example: “Kindly inform me of the final deadline.”
3. I would appreciate your update
This phrase is polite and shows that you value the other person’s time and effort.
Example: “I would appreciate your update on the client meeting.”
4. Please keep me informed
Use this when you want ongoing updates, not just a single piece of information.
Example: “Please keep me informed of any developments.”
5. I look forward to your response
This is a common closing line in formal emails. It is polite and sets a positive expectation.
Example: “I look forward to your response regarding the proposal.”
Casual Alternatives to ‘Let Me Know’
Use these with friends, family, or close coworkers. They sound friendly and natural.
1. Keep me posted
This is a very common casual phrase. It means the same as “let me know” but sounds more relaxed.
Example: “Keep me posted on the party plans.”
2. Tell me what you think
Use this when you want an opinion or feedback.
Example: “Tell me what you think about the movie.”
3. Just say the word
This is very informal and means “tell me when you are ready.”
Example: “Just say the word and I will pick you up.”
4. Give me a shout
This is a friendly, casual way to ask someone to contact you.
Example: “Give me a shout when you arrive.”
5. Drop me a line
This is an old but still common casual phrase for asking someone to write or message you.
Example: “Drop me a line when you have a minute.”
Comparison Table: Formal vs Casual
| Situation | Formal | Casual |
|---|---|---|
| Asking for a decision | Please advise on your decision. | Just tell me what you decide. |
| Asking for an update | Kindly keep me informed. | Keep me posted. |
| Asking for questions | Please do not hesitate to ask. | Let me know if you have questions. |
| Asking for availability | Please confirm your availability. | Tell me when you are free. |
| Asking for feedback | I would appreciate your feedback. | Tell me what you think. |
Natural Examples
Formal Email Example
Subject: Request for Project Update
Dear Mr. Thompson,
I hope this message finds you well. Please advise on the progress of the marketing report. Kindly inform me if there are any delays. I look forward to your response.
Best regards,
Sarah
Casual Text Message Example
Hey Mike, keep me posted on the game tonight. Just say the word if you need a ride. Drop me a line when you know the time.
Workplace Conversation Example
Formal: “Please keep me informed of any changes to the schedule.”
Casual: “Just let me know if the schedule changes.”
Common Mistakes
Mistake 1: Using “Let me know” in a very formal email
It is not wrong, but it can sound too simple. Use “Please advise” or “Kindly inform me” instead.
Incorrect: “Let me know if you have any questions.” (in a formal proposal)
Correct: “Should you have any questions, please do not hesitate to contact me.”
Mistake 2: Using a formal phrase with friends
This can sound stiff or sarcastic.
Incorrect: “Please advise on your decision about dinner.”
Correct: “Tell me what you want for dinner.”
Mistake 3: Mixing formal and casual tone in one sentence
Keep the tone consistent.
Incorrect: “Kindly keep me posted on the update.”
Correct: “Please keep me informed on the update.” (formal) OR “Keep me posted on the update.” (casual)
Better Alternatives for Specific Situations
When you need a quick answer
Formal: “I would appreciate a prompt response.”
Casual: “Get back to me soon.”
When you want someone to confirm something
Formal: “Please confirm receipt of this email.”
Casual: “Just confirm you got this.”
When you are asking for permission
Formal: “Kindly advise if this is acceptable.”
Casual: “Let me know if this works for you.”
Mini Practice Section
Choose the best option for each situation. Answers are below.
1. You are writing to your manager about a project deadline.
a) Just tell me when it is due.
b) Please advise on the deadline.
c) Drop me a line about the deadline.
2. You are texting your friend about a weekend trip.
a) Kindly inform me of your availability.
b) Please advise on your plans.
c) Keep me posted on the plans.
3. You are emailing a client about a contract.
a) Let me know if you have questions.
b) Should you have any questions, please do not hesitate to contact me.
c) Tell me if you have questions.
4. You are talking to a coworker about a lunch break.
a) I would appreciate your update on lunch.
b) Just say the word when you are ready to go.
c) Kindly advise on your lunch time.
Answers: 1-b, 2-c, 3-b, 4-b
FAQ
1. Can I use “Let me know” in a formal email?
Yes, but it is better to use a more formal alternative like “Please advise” or “Kindly inform me” to sound more professional. “Let me know” is neutral, so it is not wrong, but it is less common in very formal writing.
2. What is the most polite way to ask for an update?
“I would appreciate your update” or “Please keep me informed” are very polite. Adding “at your earliest convenience” makes it even more respectful.
3. Is “Keep me posted” too casual for work?
It depends on your workplace culture. In a relaxed office or with close colleagues, it is fine. In a very formal environment, use “Please keep me informed” instead.
4. How do I ask for a decision without sounding pushy?
Use phrases like “Please advise on your decision when you have a moment” or “I look forward to your decision at your convenience.” These show patience and respect.
For more polite everyday phrases, visit our Polite Everyday Phrases section. If you need help with professional emails, check out our Professional Email Alternatives. For workplace speaking, see our Workplace Speaking Phrases. You can also learn more about our approach on our About Us page or read our FAQ for common questions.
