Formal vs Casual Ways to Say ‘Let me know’

The phrase “Let me know” is one of the most common expressions in English, but its tone can change completely depending on how you use it. In short, the formal versions are best for emails to managers, clients, or people you do not know well, while the casual versions work well with friends, close colleagues, or in everyday conversation. This guide will help you choose the right version every time.

Quick Answer: Which Version Should You Use?

If you are writing a professional email, use “Please advise” or “I would appreciate your input”. If you are texting a friend, use “Give me a shout” or “Just tell me”. For most workplace situations, “Keep me posted” is a safe middle-ground option. The table below gives you a clear comparison.

Comparison Table: Formal vs Casual Versions

Understanding the Tone Difference

The main difference between formal and casual versions of “Let me know” is the level of directness and the relationship between the speakers. Formal versions use longer phrases, polite words like “please” and “appreciate,” and often include a full sentence structure. Casual versions are shorter, use everyday vocabulary, and sometimes include slang or phrasal verbs.

For example, if you say “Please advise on the next steps” in an email, you sound professional and respectful. If you say the same thing to a close friend, it might sound strange or too stiff. On the other hand, saying “Just tell me what you think” to your boss could seem too informal or even rude.

Formal Versions with Examples

1. Please advise

This is one of the most common formal alternatives. Use it in professional emails when you need a decision or direction.

Example: “Please advise on the deadline for the report.”

2. I would appreciate your input

This version is polite and shows that you value the other person’s opinion. It works well when asking for feedback.

Example: “I would appreciate your input on the draft proposal before we send it to the client.”

3. Kindly inform me

This is very formal and slightly old-fashioned. Use it only in very official or written communication.

Example: “Kindly inform me of the meeting schedule at your earliest convenience.”

4. Please keep me updated

This is a good choice when you want to follow the progress of a project or task.

Example: “Please keep me updated on any changes to the budget.”

5. I look forward to your response

This is a common closing line in formal emails. It is polite and sets a positive tone.

Example: “I look forward to your response regarding the contract terms.”

Casual Versions with Examples

1. Give me a shout

This is a friendly, informal way to ask someone to contact you. It is common in British and American English.

Example: “Give me a shout when you are free to chat.”

2. Just tell me

This is very direct and casual. Use it with people you know well.

Example: “Just tell me what you need and I will help.”

3. Let me know when you can

This is a relaxed version that gives the other person flexibility. It is not too formal or too casual.

Example: “Let me know when you can come over.”

4. Keep me in the loop

This is a common workplace phrase that is casual but still professional enough for many office situations.

Example: “Keep me in the loop about the project updates.”

5. Hit me up

This is very informal slang. Use it only with close friends or in very relaxed settings.

Example: “Hit me up if you want to grab coffee later.”

Natural Examples in Context

Here are some real-life situations that show how to use these phrases correctly.

Situation 1: Email to a client
“Dear Mr. Chen,
Thank you for your inquiry. Please advise on your preferred delivery date so we can arrange the shipment.
Best regards,
Sarah”

Situation 2: Text to a friend
“Hey, give me a shout when you are done with work. Let’s grab dinner.”

Situation 3: Team meeting follow-up
“Thanks everyone for the input. Please keep me updated on the action items from today.”

Situation 4: Asking a colleague for help
“I would appreciate your input on the presentation slides. Do you have time this afternoon?”

Situation 5: Casual chat with a roommate
“Just tell me if you need anything from the store.”

Common Mistakes

Many English learners make mistakes when choosing between formal and casual versions. Here are the most common ones to avoid.

Mistake 1: Using “Please advise” in casual conversation.
This sounds too stiff. Instead, say “Let me know” or “Tell me.”

Mistake 2: Using “Hit me up” in a professional email.
This is too informal and can seem disrespectful. Use “Please contact me” or “I look forward to hearing from you.”

Mistake 3: Mixing formal and casual in the same sentence.
For example, “Kindly hit me up” sounds strange. Stick to one tone.

Mistake 4: Using “Keep me in the loop” with a very senior manager.
This phrase is fine with colleagues, but with a CEO or client, use “Please keep me updated.”

Better Alternatives for Specific Situations

Sometimes you need a phrase that is not too formal and not too casual. Here are some balanced alternatives.

When you need a quick answer: “Could you let me know by tomorrow?” This is polite but direct.

When you want to be polite but not stiff: “I would love to hear your thoughts on this.” This works well in many workplace emails.

When you are following up: “Just checking in to see if you have any updates.” This is friendly and professional.

When you are asking for permission: “Please let me know if this works for you.” This is clear and respectful.

When to Use Each Version

Choosing the right version depends on three things: who you are talking to, the situation, and the channel of communication.

Use formal versions when:

• You are writing to a client, manager, or someone you do not know well.
• The situation is serious, such as a job application, contract, or official request.
• You are writing a formal email or letter.

Use casual versions when:

• You are talking to friends, family, or close colleagues.
• The situation is relaxed, such as making plans or asking for a small favor.
• You are texting or chatting on messaging apps.

Use balanced versions when:

• You are in a workplace but have a friendly relationship with the person.
• You are not sure about the level of formality.
• You want to be polite but not too distant.

Mini Practice Section

Test your understanding with these four questions. Choose the best version for each situation.

Question 1: You are writing an email to a new client about a project deadline. Which is the best choice?
A) Hit me up when you decide.
B) Please advise on the preferred deadline.
C) Just tell me when.
Answer: B. This is polite and professional for a client.

Question 2: You are texting your best friend about weekend plans. Which is the best choice?
A) I would appreciate your input on the schedule.
B) Kindly inform me of your availability.
C) Give me a shout when you know your plans.
Answer: C. This is friendly and casual.

Question 3: You are in a team meeting and want to follow up on tasks. Which is the best choice?
A) Please keep me updated on the progress.
B) Just tell me what you did.
C) Hit me up later.
Answer: A. This is professional but not too stiff for a team setting.

Question 4: You are asking a colleague for feedback on a document. Which is the best choice?
A) I would appreciate your input on this draft.
B) Give me a shout about it.
C) Let me know when you can.
Answer: A. This is polite and shows respect for the colleague’s time.

Frequently Asked Questions

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

Yes, but it is better to use a more formal version like “Please advise” or “I would appreciate your input” in very formal situations. “Let me know” is acceptable in semi-formal emails.

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

“Keep me posted” is a balanced phrase. It is common in workplace communication and is not too formal or too casual. It works well with colleagues and managers.

3. What is the most polite way to say “Let me know”?

The most polite versions are “I would appreciate your input” and “Kindly inform me.” These show respect and patience.

4. Can I use “Give me a shout” in a business email?

No, “Give me a shout” is too casual for most business emails. Use it only with close colleagues in informal messages or conversation.

For more help with everyday polite phrases, visit our Polite Everyday Phrases section. If you need professional email alternatives, check out our Professional Email Alternatives guide. For workplace situations, see our Workplace Speaking Phrases page. You can also learn more about our approach on our About Us page or read our Editorial Policy.