Formal vs informal English: three levels, and how to pick one

Quick take: formality is a scale, not a switch. Most real writing (work emails, application letters, IELTS Task 2) sits in the middle: neutral English with no slang and no contractions, but no stiff phrases either. Write to the reader, not to impress them, and keep one level from the greeting to the sign-off.

Most word lists split English into two columns, formal and informal. In practice there are three levels, and the middle one is the one you will use most. The common mistake for learners is not being too casual. It is being too formal in the wrong places.

Three levels, one message

Here is the same request written three ways.

Formal, for a stranger or an institution: a council, an embassy, a hiring manager you have not met.

I am writing to request an extension to the deadline for my application. I would be grateful if you could confirm whether this is possible.

Neutral, for someone you know in a work or study role: a manager, a lecturer, a landlord.

Could I have a few more days for my application? I'd be grateful if you could let me know.

Informal, for a friend or family member.

Any chance I can hand this in a few days late? Let me know!

The facts do not change. What changes is sentence length, how direct the request is, contractions, and vocabulary.

Word swaps that change the level

The quickest way to raise the level is to replace phrasal verbs and vague words with a single precise verb.

Two grammar features also mark the level:

• Contractions. Use "do not", "it is" and "I would" in formal writing. "Don't" and "it's" are fine in neutral emails and normal in informal ones.
• Direct questions and commands. "Send me the form" is informal. "Could you send me the form?" is neutral. "I would be grateful if you could send me the form" is formal.

Do not swap every word. "Utilise" is not better than "use", and "commence" is not better than "start". Formal means precise and complete, not long.

The over-formal trap

Many learners, especially those taught from older letter-writing books, write in a level that native readers find old-fashioned or even unclear. These phrases are the usual signs:

None of these is a grammar error, but they make the writer sound unsure of the level. In an IELTS letter, an essay or a job application, plain and polite reads as more confident. The email to a professor guide has more examples of the same problem.

Which level, where

In IELTS General Training, tone is part of Task Achievement: the examiner checks that it suits the reader and stays consistent. Mixing levels ("Dear Sir or Madam" then "Hope you're doing great!") is one of the most common ways to lose marks. The letter checker works out the tone a task needs and checks yours against it.

Mixing levels: a quick test

Read your first and last sentences together. If one would sound strange next to the other, the level has drifted. Then check three things:

1. Greeting and sign-off match. "Dear Sir or Madam" pairs with "Yours faithfully", a name with "Yours sincerely" or "Best regards", a friend with "Best wishes" or "See you soon".
2. No contractions in formal writing, none missing in informal writing where they would be natural.
3. One word for one idea. If you wrote "kids" in one paragraph and "children" in another, pick the one that suits the reader.

Formal writing still needs plain words. When a formal phrase and a simple word mean the same thing, use the simple word. The commonly confused words guide and the paraphrasing guide help with the precise word when you need one.

Check your level

For an essay, paste it into the essay checker for an estimated band on each criterion, with word-choice problems marked. For a letter, the letter checker checks the tone against the reader in your task.