Formal vs. Informal Writing: Differences, Examples, and When to Use Each

Formal writing is polished, professional, and usually follows standard grammar closely. Informal writing is more relaxed, conversational, and personal.

Formal: I am writing to request additional information.
Informal: I’m writing to ask for more info.

Both styles are useful. The right choice depends on your audience, purpose, and situation. A college essay, business proposal, or job application usually needs formal writing. A text message, friendly email, or casual social post can be informal.

Formal vs. informal writing at a glance

Style	Best for	Example
formal writing	school, business, legal, official, academic	Please review the attached document.
informal writing	friends, quick messages, casual posts	Check out the file I sent.

Quick rule:

Use formal writing when the situation is professional, academic, official, or serious.
Use informal writing when the situation is casual, personal, or friendly.
When unsure, choose a slightly more formal tone.

What is formal writing?

Formal writing is a style used for professional, academic, and official communication. It usually avoids slang, overly casual phrases, and unclear shortcuts.

Formal writing often has:

complete sentences
clear structure
precise word choice
polite tone
fewer contractions
fewer personal expressions
standard grammar and punctuation

Examples:

Thank you for your consideration.
The report explains the main causes of the issue.
Please contact our office if you have any questions.
This study examines the relationship between sleep and memory.

Formal writing is not the same as complicated writing. Good formal writing should still be clear and easy to read.

What is informal writing?

Informal writing is a relaxed style used in everyday communication. It can sound more personal, friendly, and conversational.

Informal writing often has:

contractions
simple everyday words
casual expressions
shorter sentences
personal opinions
direct address
a friendly tone

Examples:

Thanks for your help!
I’ll send it over soon.
That idea sounds great.
Let me know what you think.

Informal writing is useful when you want to sound warm, natural, and approachable.

Key differences between formal and informal writing

The main difference is tone. Formal writing sounds professional and controlled. Informal writing sounds relaxed and conversational.

Feature	Formal writing	Informal writing
Tone	professional	casual
Vocabulary	precise	everyday
Contractions	usually limited	common
Slang	avoided	sometimes used
Sentence style	complete and polished	shorter and looser
Audience	teachers, employers, clients, officials	friends, coworkers you know well, casual readers
Purpose	explain, persuade, report, request	chat, share, respond, connect

Neither style is always better. The better style is the one that fits the reader.

Examples: formal vs. informal sentences

Here are common informal sentences rewritten in a more formal style.

Informal	Formal
I need the file ASAP.	Please send the file as soon as possible.
Sorry, I can’t make it.	I apologize, but I am unable to attend.
This project is kind of confusing.	This project requires further clarification.
We messed up the schedule.	The schedule was not followed as planned.
Can you check this out?	Could you please review this?
Thanks a lot!	Thank you for your assistance.

Notice that formal writing is not rude or cold. It is usually more careful, complete, and specific.

When should you use formal writing?

Use formal writing when your reader expects professionalism, accuracy, or respect.

Good situations for formal writing include:

academic essays
research papers
business proposals
cover letters
resumes
client emails
official complaints
legal or policy documents
reports
scholarship applications

Examples:

I am applying for the marketing assistant position.
This report summarizes the results of the survey.
We respectfully request an extension of the deadline.

Formal writing is especially important when your words may be reviewed, graded, archived, forwarded, or used as an official record.

When should you use informal writing?

Use informal writing when the situation is relaxed and the relationship is personal or familiar.

Good situations for informal writing include:

text messages
friendly emails
casual team chats
personal notes
social media captions
comments to friends
quick reminders

Examples:

I’ll call you later.
Thanks! That helps a lot.
Can we move the meeting to Friday?

Informal writing can still be correct and respectful. Casual does not have to mean careless.

Formal writing in emails

Email tone depends on who will read the message. A message to a professor, hiring manager, client, or new contact should usually be formal or semi-formal.

Informal:

Hey, can you send me the details?

Formal:

Hello Dr. Smith, could you please send me the details when you have a chance?

Informal:

I got your message. Sounds good.

Formal:

Thank you for your message. The proposed plan sounds good to me.

In email, a safe middle style is often best: polite, clear, and not too stiff.

Formal writing in academic work

Academic writing usually needs a formal style. That means you should avoid slang, vague words, and overly personal language unless your assignment allows it.

Informal:

This article talks about how sleep is super important.

Formal:

This article explains why sleep is important for health and memory.

Informal:

I think the author did a good job.

Formal:

The author presents a clear and well-supported argument.

Academic writing should focus on evidence, explanation, and clarity.

Common mistakes

Mistake 1: Making formal writing too complicated

Formal writing should be clear, not heavy.

Too complicated: It is incumbent upon the participants to facilitate communication.

Better: Participants should communicate clearly.

Mistake 2: Using slang in formal writing

Informal: The results were awesome.

Formal: The results were significant.

Mistake 3: Being too casual with a serious reader

Informal: Hey, I need this fixed today.

Formal: Hello, could you please address this issue today?

Mistake 4: Thinking informal writing can be sloppy

Informal writing can use a friendly tone, but it should still be understandable.

Weak: yeah idk send it whenever

Better: Sure, send it whenever you can.

Quick quiz

Choose the better style.

You are emailing a professor about a missed assignment.
You are texting a close friend about lunch.
You are writing a cover letter.
You are posting a casual vacation caption.
You are sending a report to a client.

Answers:

formal
informal
formal
informal
formal

FAQ

What is the difference between formal and informal writing?

Formal writing is professional, polished, and often used in academic or official situations. Informal writing is relaxed, friendly, and used in casual communication.

Is formal writing always better?

No. Formal writing is better for serious, professional, or academic situations. Informal writing is better for friendly and casual situations.

Can formal writing use contractions?

Sometimes, but many formal contexts avoid contractions. For a very formal essay, write do not instead of don’t.

Is informal writing grammatically wrong?

No. Informal writing can still be grammatically correct. It simply uses a more relaxed tone.

What tone should I use in business emails?

Use a polite, clear, semi-formal tone unless you know the reader well.

How do I make informal writing more formal?

Use complete sentences, remove slang, choose precise words, and make the tone more polite.

The same context-first habit also helps with Calendar vs. Calender and Maintenance vs. Maintainance. For a wider set of examples in this topic, use the Business & Academic English archive as the category grows.

Final tip

Use formal writing when you need to sound professional, respectful, academic, or official.

Use informal writing when you are communicating casually with people who know you well.

If you are unsure, choose a clear, polite, semi-formal style. It is usually safe for business and academic communication.