The phrase “Let me know” is one of the most common requests in English, but its tone can change dramatically depending on the situation. In short, use “Let me know” for casual conversations with friends or colleagues you know well. For formal writing, emails to superiors, or professional correspondence, choose alternatives like “Please advise,” “I would appreciate your input,” or “Kindly inform me.” This guide will give you the exact phrases to use in each context, with examples and common pitfalls to avoid.
Quick Answer: Which Phrase Should You Use?
If you need a fast decision, here is a simple guide:
- Casual (friends, close coworkers, text messages): “Let me know,” “Just tell me,” “Give me a shout.”
- Semi-formal (everyday work emails, team chats): “Please let me know,” “Keep me posted,” “I’d like to hear your thoughts.”
- Formal (business letters, emails to clients or superiors, academic writing): “Please advise,” “I would appreciate your feedback,” “Kindly inform me,” “Awaiting your response.”
Understanding the Tone: Formal vs Casual
The key difference between formal and casual versions of “Let me know” is the level of directness and politeness. Casual versions are short, direct, and assume a close relationship. Formal versions are longer, more indirect, and show respect for the reader’s time and authority. Using the wrong tone can make you sound rude or overly stiff.
Casual Tone
Casual phrases are best for people you know well. They are common in text messages, instant messaging apps, and informal conversations. They often drop the word “please” and use contractions or slang.
Formal Tone
Formal phrases are used in professional emails, letters, and official communication. They include polite words like “please,” “kindly,” and “appreciate.” They often use full sentences and avoid contractions.
Comparison Table: Formal vs Casual Ways to Say ‘Let me know’
| Casual | Formal | Best Used In |
|---|---|---|
| Let me know. | Please advise. | Emails to managers, clients, or professors. |
| Just tell me what you think. | I would appreciate your feedback on this matter. | Professional requests for opinions or reviews. |
| Give me a shout when you’re free. | Kindly inform me of your availability. | Scheduling meetings or calls. |
| Keep me in the loop. | Please keep me updated on any developments. | Project updates or ongoing tasks. |
| Let me know if you need anything. | Please do not hesitate to reach out if you require further assistance. | Customer service or support emails. |
Natural Examples in Context
Seeing these phrases in real situations helps you understand when to use each one.
Casual Examples
- Text to a friend: “Hey, I’m thinking of ordering pizza. Let me know if you want some.”
- Slack message to a teammate: “I finished the draft. Just tell me if anything looks off.”
- Conversation with a coworker: “Give me a shout when you’re ready to review the slides.”
Formal Examples
- Email to a client: “Please advise on the preferred delivery date for the shipment.”
- Email to a supervisor: “I would appreciate your feedback on the attached proposal before the meeting.”
- Letter to a vendor: “Kindly inform us of your decision regarding the contract renewal.”
Common Mistakes to Avoid
Even advanced learners make these errors. Here are the most frequent ones:
Mistake 1: Using “Let me know” in very formal writing
Incorrect: “Let me know if you approve the budget.” (Too casual for a formal request to a director.)
Correct: “Please advise on your approval of the budget.”
Mistake 2: Adding “please” but keeping the tone too direct
Incorrect: “Please let me know your decision by Friday.” (Still sounds a bit blunt for a formal email.)
Correct: “I would appreciate receiving your decision by Friday.”
Mistake 3: Using “Kindly” incorrectly
Incorrect: “Kindly let me know if you can come.” (This mixes formal and casual tones awkwardly.)
Correct: “Kindly confirm your attendance.” (Use “kindly” with a clear action verb.)
Mistake 4: Overusing “Please advise”
Incorrect: “Please advise on the report.” (Too vague; the reader doesn’t know what you need.)
Correct: “Please advise on the next steps for the report.” (Be specific.)
Better Alternatives for Specific Situations
Sometimes you need more than just a direct replacement. Here are alternatives for common scenarios:
When requesting a decision
- Casual: “Let me know what you decide.”
- Formal: “I look forward to your decision.” or “Please inform me of your final decision.”
When asking for feedback
- Casual: “Tell me what you think.”
- Formal: “I would value your input on this matter.” or “Your feedback would be greatly appreciated.”
When checking for updates
- Casual: “Keep me posted.”
- Formal: “Please keep me apprised of any changes.” or “I would appreciate being kept informed.”
When to Use Each Version
Choosing the right phrase depends on three factors: your relationship with the reader, the medium, and the urgency.
- Relationship: Use casual with friends, close colleagues, and in informal teams. Use formal with superiors, clients, and people you don’t know well.
- Medium: Text messages and instant chats are almost always casual. Emails can be casual or formal depending on the recipient. Letters and official documents are always formal.
- Urgency: In urgent situations, even formal emails can use slightly shorter phrases, but still keep the polite tone. For example, “Please advise urgently” is acceptable in a formal context.
Mini Practice Section
Test your understanding with these four questions. Choose the best phrase for each situation.
Question 1
You are writing an email to your company’s CEO about a project deadline. What is the best way to ask for their input?
A) Let me know what you think.
B) I would appreciate your guidance on the deadline.
C) Just tell me when you want it done.
Answer: B) “I would appreciate your guidance on the deadline.” This is polite and formal, suitable for a superior.
Question 2
You are texting a friend about weekend plans. What is the most natural phrase?
A) Kindly inform me of your availability.
B) Let me know if Saturday works for you.
C) Please advise on your preferred day.
Answer: B) “Let me know if Saturday works for you.” This is casual and natural for a friend.
Question 3
You need to ask a client for their decision on a proposal. Which option is most appropriate?
A) Give me a shout when you decide.
B) Please advise on your decision regarding the proposal.
C) Tell me what you want to do.
Answer: B) “Please advise on your decision regarding the proposal.” This is formal and respectful for a client.
Question 4
You are in a team meeting and want a colleague to update you later. What is a good semi-formal option?
A) Keep me posted on the progress.
B) I demand an update by tomorrow.
C) Kindly inform me of any developments at your earliest convenience.
Answer: A) “Keep me posted on the progress.” This is semi-formal and works well in a workplace conversation.
Frequently Asked Questions
1. Is “Let me know” ever acceptable in formal writing?
Yes, but only if you add “please” and the context is not extremely formal. For example, “Please let me know if you have any questions” is acceptable in many professional emails. However, for very formal letters or emails to high-level executives, choose a more formal alternative.
2. What is the difference between “Please advise” and “Please let me know”?
“Please advise” is more formal and often implies you are asking for a decision or specific guidance. “Please let me know” is slightly less formal and can be used for general requests. In formal writing, “Please advise” is preferred.
3. Can I use “Kindly” in casual conversations?
No. “Kindly” sounds very formal and old-fashioned. Using it in casual conversation can sound sarcastic or unnatural. Stick to “please” or just the direct phrase.
4. How do I ask for an update without sounding rude?
Use polite phrases like “I was wondering if you have any updates” or “Could you please provide an update when you have a moment?” Avoid demanding language like “Update me now” or “Let me know immediately.”
For more help with polite everyday phrases, visit our Polite Everyday Phrases section. If you need professional email alternatives, check out our Professional Email Alternatives category. For workplace speaking, see Workplace Speaking Phrases. And for more comparisons like this one, visit Formal and Casual Versions.
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