What is the difference between formal and informal language?

Formal language is careful, precise, and professional. You use it in essays, job applications, official letters, and exams. Informal language is relaxed and conversational — you use it with friends, in text messages, and in casual speech. The words mean the same thing, but they carry different levels of seriousness.

Can I use informal words in IELTS Writing?

No. IELTS Writing Task 1 and Task 2 require formal language. Using contractions like 'don't' or 'can't', slang, or informal phrases like 'a lot of' will lower your score. Replace them with formal equivalents: 'do not', 'cannot', 'a significant number of'.

What words should I avoid in formal writing?

Avoid contractions (don't, can't, won't), slang (loads of, tons of, pretty), informal connectors (also, plus, so), vague words (thing, stuff, get, put), and first-person casual phrases (I think, I feel, in my opinion). Replace them with their formal equivalents.

Is 'a lot of' formal or informal?

'A lot of' is informal. In formal writing and IELTS essays, replace it with: a significant number of, a considerable amount of, numerous, a great deal of, or a substantial proportion of — depending on whether you are talking about countable or uncountable things.

Formal vs Informal Words — Complete List with Examples

The short answer

Formal and informal words often mean the same thing — but they carry a different level of seriousness. Using informal words in a formal essay or exam is like wearing flip-flops to a job interview. The content might be fine. But the impression is wrong.

What is the difference?

Every language has two modes. Think of it like two different outfits for the same person.

Informal language

•Used with friends and family
•Text messages and casual speech
•Relaxed, conversational, natural
•Contractions: don't, can't, it's
•Slang: loads of, pretty, stuff

“The government's new plan is gonna help loads of people get better jobs.”

Formal language

•Used in essays, exams, official letters
•Academic and professional writing
•Careful, precise, professional
•No contractions: do not, cannot, it is
•Standard vocabulary: numerous, obtain, utilise

“The government's new initiative is expected to assist a significant number of individuals in securing employment.”

The 3 biggest informal mistakes in formal writing

These are the errors that Grammarly, IELTS examiners, and SSC setters all look for.

Contractions

A contraction is when two words are joined with an apostrophe — don't, can't, won't, it's. They are perfectly normal in speech. But in formal writing, they signal carelessness.

Informal ✗

The policy can't work because it doesn't address the root cause.

Formal ✓

The policy cannot work because it does not address the root cause.

Vague quantity words

'A lot of', 'tons of', 'loads of' — these are fine in conversation. In a formal essay, they make your argument sound weak and imprecise.

Informal ✗

A lot of people are affected by this problem.

Formal ✓

A significant proportion of the population is affected by this issue.

Personal opinion phrases

'I think', 'I feel', 'in my opinion' — in IELTS Academic Writing, you should present ideas as facts or logical arguments, not as personal feelings.

Informal ✗

I think the government should invest more in education.

Formal ✓

It could be argued that greater investment in education is essential.

The master word swap list — 30 informal → formal replacements

Bookmark this. Every time you write a formal essay, run through this list and check your word choices.

Informal (avoid)	Formal (use instead)
a lot of / lots of	a significant number of / numerous / a considerable amount of
get	obtain / receive / acquire
give	provide / offer / present
show	demonstrate / illustrate / indicate
find out	discover / determine / ascertain
look into	investigate / examine / analyse
go up / rise	increase / escalate / surge
go down / fall	decrease / decline / diminish
big / huge	significant / substantial / considerable
small / tiny	minor / minimal / negligible
bad	detrimental / adverse / unfavourable
good	beneficial / advantageous / favourable
need	require / necessitate
help	assist / facilitate / support
use	utilise / employ / apply
think	consider / believe / argue / contend
say / tell	state / assert / claim / maintain
start / begin	initiate / commence / establish
end / stop	conclude / cease / terminate
make	produce / generate / create / construct
try	attempt / endeavour / strive
kids / children	children / young people / minors
a bit	slightly / somewhat / marginally
really / very	extremely / particularly / significantly
okay / fine	acceptable / adequate / satisfactory
also / plus	furthermore / moreover / in addition
but / so	however / therefore / consequently / thus
because	because / since / as / owing to the fact that
I think	It could be argued that / It is evident that
in my opinion	From this perspective / It appears that

Exam tip — IELTS Writing Band 7+

IELTS examiners specifically check for lexical resource— the range and accuracy of vocabulary. Using the same informal word repeatedly (especially “get”, “big”, “a lot of”) keeps you at Band 5–6. To reach Band 7+, replace them with precise formal vocabulary from this list. One rule: only use a word you understand well enough to use correctly. Guessing at formal words causes worse errors than using simple ones.

🤖 AI writing tip

When Grammarly or ChatGPT flags a word as “too informal”, it is looking at register — the level of formality. The suggestion it gives is usually correct. But always check: does the formal replacement mean exactly the same thing in context? Sometimes the suggested word is slightly different in meaning. Accept it only if it fits perfectly.

Formal vs Informal Words — Complete List

What is the difference?

The 3 biggest informal mistakes in formal writing

The master word swap list — 30 informal → formal replacements

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