Formal vs Casual Ways to Say ‘Let me know’

If you want to ask someone to tell you something later, the phrase “Let me know” works in many situations. However, the way you say it changes depending on whether you are writing a professional email, speaking to a colleague, or chatting with a friend. This guide gives you direct formal and casual alternatives to “Let me know,” with clear examples and context so you can choose the right phrase every time.

Quick Answer: Formal vs Casual Versions

Use “Please keep me informed” or “I would appreciate your update” in formal writing and professional emails. Use “Just tell me” or “Give me a shout” in casual conversation with friends or close coworkers. The table below shows the main differences at a glance.

Comparison Table: Formal vs Casual Alternatives

When to Use Formal Alternatives

Formal alternatives to “Let me know” are best for professional emails, official letters, academic writing, or any situation where you want to show respect and maintain a polite distance. These phrases sound more careful and considerate. They also help you avoid sounding too demanding or casual with people you do not know well.

1. Please keep me informed

This phrase is direct but polite. Use it when you expect a future update and want to sound professional without being pushy.

Example: “Please keep me informed about the project timeline.”

2. I would appreciate your update

This is a softer request. It shows that you value the other person’s effort to share information.

Example: “I would appreciate your update once the review is complete.”

3. Kindly notify me

Use this in very formal or official settings, such as legal or administrative communication.

Example: “Kindly notify me when the documents are ready for signature.”

4. Please advise

Common in business emails, especially when you need a decision or instruction.

Example: “Please advise on the next steps for the contract renewal.”

When to Use Casual Alternatives

Casual alternatives are perfect for friends, family, close colleagues, or informal group chats. They sound friendly, relaxed, and natural. Using a formal phrase in a casual setting can feel stiff or distant.

1. Just tell me

Simple and direct. Use this when you want a quick answer from someone you are comfortable with.

Example: “Just tell me if you can come to the party.”

2. Give me a shout

Very common in British and American casual speech. It means “contact me” or “let me know.”

Example: “Give me a shout when you arrive at the station.”

3. Keep me posted

This is a friendly way to ask for updates without pressure.

Example: “Keep me posted about your travel plans.”

4. Let me know when you can

A softer casual version that gives the other person flexibility.

Example: “Let me know when you can, no rush.”

Natural Examples in Context

Seeing the phrases in real situations helps you understand the tone and nuance. Below are examples for both formal and casual settings.

Formal Email Example

Subject: Update on Client Meeting

Dear Ms. Chen,

Thank you for your time yesterday. Please keep me informed about the client’s feedback. I would appreciate your update by Friday so we can prepare the proposal accordingly.

Best regards,

James

Casual Conversation Example

Friend: “I’m not sure if I can make it to dinner.”

You: “No problem, just tell me when you know. Give me a shout before 6.”

Workplace Speaking Example

Colleague: “I’ll check the inventory numbers.”

You: “Great, keep me posted. No hurry.”

Common Mistakes

English learners often make small errors when using these alternatives. Here are the most frequent mistakes and how to fix them.

Mistake 1: Mixing formal and casual tone in the same sentence

Wrong: “Kindly notify me when you get a sec.”

Right: “Kindly notify me when you have the information.” (formal) OR “Just tell me when you get a sec.” (casual)

Mistake 2: Using “Please advise” too broadly

“Please advise” is best for asking for a decision or instruction. Do not use it for simple updates.

Wrong: “Please advise when the package arrives.”

Right: “Please let me know when the package arrives.” or “Please keep me informed about the delivery.”

Mistake 3: Forgetting the preposition with “keep me posted”

Wrong: “Keep me posted about the meeting.” (This is actually correct, but learners sometimes say “Keep me posted on” which is also fine. The mistake is using it without any context.)

Better: “Keep me posted on the meeting outcome.”

Mistake 4: Using “Give me a shout” in a formal email

Wrong: “Dear Mr. Thompson, give me a shout when you have the report.”

Right: “Dear Mr. Thompson, please keep me informed when the report is ready.”

Better Alternatives for Specific Situations

Sometimes you need a phrase that fits a very specific context. Here are targeted alternatives.

For asking about availability

Formal: “Please indicate your availability for next week’s meeting.”

Casual: “Tell me when you’re free.”

For requesting a decision

Formal: “I await your decision at your earliest convenience.”

Casual: “Just say yes or no when you decide.”

For following up after a meeting

Formal: “I look forward to your update on the action items.”

Casual: “Let me know how it goes.”

Mini Practice: Choose the Right Phrase

Test your understanding. Choose the best alternative for each situation.

1. You are writing to your manager about a project deadline.

A. Give me a shout when you decide.

B. Please keep me informed of your decision.

C. Just tell me what you think.

Answer: B. This is a formal workplace situation, so “Please keep me informed” is appropriate.

2. You are texting a friend about weekend plans.

A. Kindly notify me of your plans.

B. Please advise on your availability.

C. Give me a shout when you know.

Answer: C. Casual and friendly works best with friends.

3. You need a client to confirm a contract term.

A. Just tell me if it’s okay.

B. Please advise on the contract term.

C. Keep me posted, no rush.

Answer: B. “Please advise” is standard in business correspondence.

4. You are asking a colleague for a quick update in the office.

A. I would appreciate your update when you have a moment.

B. Kindly notify me immediately.

C. Give me a shout later.

Answer: A. This is polite but not overly formal, suitable for a workplace conversation.

Frequently Asked Questions

1. Can I use “Let me know” in formal emails?

Yes, “Let me know” is acceptable in many formal emails, especially if you add “please.” However, for very formal or official communication, it is better to use alternatives like “Please keep me informed” or “I would appreciate your update.”

2. Is “Keep me posted” formal or casual?

“Keep me posted” is casual to neutral. It is fine in workplace conversations with colleagues you know well, but avoid it in formal letters or emails to senior management or clients.

3. What is the most polite way to ask for an update?

The most polite way is “I would appreciate your update when you have a moment.” It shows respect for the other person’s time and is suitable for almost any professional situation.

4. Can I use “Please advise” in an email to a friend?

It sounds unnatural and too formal. Use “Let me know” or “Tell me” instead. “Please advise” is best for business or official requests.

Final Tips for Choosing the Right Phrase

Think about your relationship with the person and the context. If you are unsure, choose a neutral option like “Please let me know” or “Keep me posted.” These work in most situations without sounding too stiff or too casual. Practice using the alternatives in real emails and conversations to build your confidence. For more guidance on formal and casual language, explore our Formal and Casual Versions category. You can also find additional tips in our FAQ section or learn about our editorial policy.