Formal vs Informal English
Level B2 · Advanced Structures
Register is the level of formality that a piece of writing or speech uses, and choosing the right register for the situation is a separate skill from getting the grammar correct — a grammatically perfect sentence can still sound wrong if it is too casual for a job application or too stiff for a text to a friend. Formal English belongs in business emails, academic essays, official letters, reports, and communication with someone you do not know well or who holds authority over you; informal English belongs in text messages, chats with friends and family, and casual spoken conversation. The two registers differ in vocabulary, grammar, and tone, and a fluent speaker switches between them automatically depending on who they are addressing and why.
Informal English is built from short, everyday language: contractions such as don't, it's, and I'll replace the full forms do not, it is, and I will; phrasal verbs such as find out, put off, and get in touch with replace their single-word equivalents; and requests tend to be direct, as in Can you send me the file? or Where's the station? Formal English avoids all of this. Contractions are spelled out in full (do not, it is, we will), phrasal verbs are usually replaced by a single-word Latinate synonym (discover, postpone, contact), and vocabulary is generally more precise and less colloquial. Requests and questions become indirect and softened with a polite frame rather than stated bluntly, as in Would you mind sending me the file? or I was wondering whether you could tell me the way to the station? Formal writing also leans more heavily on the passive voice than informal writing does — We regret to inform you that your order has been delayed reads as formal partly because the cause of the delay is left unstated, an effect covered in full in the topic on the passive voice; here it is simply one more signal, alongside vocabulary and directness, that a text belongs to the formal register.
Some of the most useful formal/informal pairs to learn, since the same idea is expressed in completely different words depending on the register:
- find out (informal) / discover (formal): Can you find out what time the meeting starts? / We would like to discover the cause of the delay.
- put off (informal) / postpone (formal): Let's put off the meeting until Friday. / We regret to inform you that the meeting has been postponed.
- get in touch with (informal) / contact (formal): I'll get in touch with you next week. / Please do not hesitate to contact us with any questions.
- a lot of (informal) / numerous (formal): There are a lot of problems with this plan. / The report identifies numerous problems with this plan.
- kids (informal) / children (formal): The kids loved the trip. / The programme is designed for children aged five to eleven.
- buy (informal) / purchase (formal): Where did you buy that? / Customers may purchase tickets online.
- ask for (informal) / request (formal): Can I ask for a refund? / I am writing to request a refund.
- get better (informal) / improve (formal): Her English has really got better. / Test scores have improved significantly since the change.
- look into (informal) / investigate (formal): We'll look into it and get back to you. / The committee has agreed to investigate the complaint.
- sort out (informal) / resolve (formal): We'll sort it out by tomorrow. / The dispute was resolved through mediation.
The most common mistake is mixing registers within the same piece of writing — starting a job application with Hey there! and then switching to elaborate formal vocabulary for the rest of the letter, or writing a formal business email that opens Dear Mr. Davis but then says we'll get back to you asap and can't guarantee it, mixing a formal salutation with a contraction and an informal abbreviation. Once a register is chosen for a piece of writing, it should stay consistent from the first line to the last. A formal email should not suddenly use kids, a lot of, or a phrasal verb like sort out, just as a casual text to a friend should not suddenly say I would be delighted to inform you that I am currently occupied. The inconsistency itself, not either register alone, is what sounds wrong to a reader.
To identify the register of a piece of English, look first at contractions: their presence signals informal, their total absence signals formal. Then check the verbs — phrasal verbs such as find out, put off, and get in touch with point to informal writing, while single-word Latinate equivalents such as discover, postpone, and contact point to formal writing. Look at how requests are phrased: a direct imperative or question (Send me the file; Can you help?) is informal, while a softened, indirect frame (Would you mind…? I was wondering if…) is formal. Finally, notice the passive voice and the overall vocabulary — frequent passive constructions and precise, less everyday words such as numerous, purchase, and resolve point to a formal register, while their everyday counterparts a lot of, buy, and sort out point to an informal one.