B2 idioms: natural expressions and when to use them

Q: What is the difference between an idiom and a phrasal verb?

A phrasal verb is a verb plus a particle (*give up*, *get over*). An idiom is any fixed expression whose meaning isn't obvious from its words (*a piece of cake*). Some phrasal verbs are idiomatic too. Practise phrasal verbs with our [phrasal verb trainer](/tools/phrasal-verb-trainer/).

B2 idioms are fixed expressions, such as a piece of cake or on the tip of my tongue, whose meaning is not obvious from the individual words. They are mostly informal, so use them sparingly: one or two in speaking or an informal email sound natural, but essays and reports need neutral language. This page is part of our B2 vocabulary guide and gives you 47 useful idioms with original examples.

By Eleanor BennettLast updated: 13 October 2026

What idioms are, and why register matters

An idiom is a group of words with a meaning you can't guess from the separate words: if a test was a piece of cake, it was very easy, and there was no cake. Idioms are part of natural, everyday English, so learning a set of common ones helps you understand speakers in the Listening paper and adds colour to your speaking.

But there is an important warning. Most idioms are informal. In the exam, register is part of how well you communicate:

Speaking: one or two idioms, used correctly and naturally, can show range. Don't plan to use them in every answer.
Informal writing (an email to a friend, a story, a lively article): an idiom here and there is appropriate.
Essays and reports: avoid most idioms. It's raining cats and dogs or it costs an arm and a leg will sound wrong in a neutral or formal text. Use plain, precise vocabulary instead.

A wrong idiom (it's a piece of cakes, I'm on the cloud nine) is worse than no idiom, because the words of an idiom are fixed. Learn each one exactly, with an example. You will find topic-related idioms on other pages too, for example in relationships vocabulary (see eye to eye) and money and shopping vocabulary (make ends meet).

Useful B2 idioms by meaning

Use it to…	Phrases
Easy and difficult	a piece of cake – very easy. The first part of the test was a piece of cake. easier said than done – easy to suggest, hard to do. 'Just relax.' 'That's easier said than done.' an uphill struggle – a long, difficult effort. Learning to drive was an uphill struggle for me. learn the ropes – learn how to do a new job or activity. It took me a month to learn the ropes at the café. get the hang of something – learn how to do something. I'm finally getting the hang of the guitar. in at the deep end – in a difficult situation with no preparation. On my first day they threw me in at the deep end. not rocket science – not complicated. Changing a tyre isn't rocket science.
Feelings and moods	over the moon – very happy. She was over the moon about her results. on cloud nine – extremely happy. He's been on cloud nine since the wedding. (no article: not 'on the cloud nine') down in the dumps – sad. You look a bit down in the dumps. What's wrong? have butterflies in your stomach – feel nervous. I always have butterflies before a presentation. get on someone's nerves – annoy someone. His loud music really gets on my nerves. keep your cool / lose your temper – stay calm / get angry. be fed up (with) – be annoyed or bored with something that has continued too long. I'm fed up with this rain. let off steam – do something to release stress. I go running to let off steam.
Success, failure and effort	pull your weight – do your fair share of work. One member of our group didn't pull his weight. go the extra mile – make more effort than expected. The hotel staff really went the extra mile. hit the nail on the head – describe something exactly right. You've hit the nail on the head. miss the boat – lose an opportunity by being too slow. Tickets sold out, so we missed the boat. back to square one – back to the start after a failure. The plan didn't work, so we're back to square one. burn the midnight oil – work late into the night. I burned the midnight oil before the deadline. give something a shot – try something. I've never surfed, but I'll give it a shot. by the skin of your teeth – only just. I passed by the skin of my teeth.
Time and decisions	once in a blue moon – very rarely. I only eat fast food once in a blue moon. in the nick of time – just before it was too late. We caught the train in the nick of time. call it a day – stop working for now. We're all tired; let's call it a day. sleep on it – wait until tomorrow to decide. Don't answer now. Sleep on it. on the fence – unable to decide. I'm still on the fence about which course to take. make up your mind – decide. Have you made up your mind about the trip? a last-minute decision – a decision made very late. Going to the festival was a last-minute decision. sooner or later – at some time in the future. Sooner or later you'll have to tell her.
Knowledge, memory and communication	on the tip of my tongue – almost remembered. His name is on the tip of my tongue. ring a bell – sound familiar. Does the name of the street ring a bell? know something inside out – know it very well. She knows the city inside out. get the wrong end of the stick – misunderstand. I think you've got the wrong end of the stick. beat around the bush – avoid saying something directly. Stop beating around the bush and tell me. speak your mind – say honestly what you think. break the ice – make people feel relaxed when they first meet. We played a game to break the ice. keep someone in the loop – keep someone informed. Please keep me in the loop about the plans.
Money, cost and people	cost an arm and a leg – be very expensive. Concert tickets cost an arm and a leg these days. tighten your belt – spend less money. We'll have to tighten our belts this month. see eye to eye – agree. My brother and I rarely see eye to eye on politics. get on like a house on fire – get on extremely well. The two cousins got on like a house on fire. the black sheep (of the family) – the person who is different and often disapproved of. a couch potato – someone who watches a lot of TV and is not active. in the same boat – in the same difficult situation. Don't worry, we're all in the same boat. give someone a hand – help. Can you give me a hand with these boxes?

Common mistakes with idioms

Trap: Changing the words of an idiom: It was a piece of cakes. / I'm on the cloud nine.
Fix: Idioms are fixed. Learn the exact form, including articles and prepositions: a piece of cake, on cloud nine.
Trap: Using idioms in an essay or report: Public transport costs an arm and a leg.
Fix: In formal or neutral writing, use plain language: Public transport is very expensive. Save idioms for speaking and informal emails.
Trap: Translating an idiom from your own language word for word.
Fix: Idioms rarely translate directly. Spanish, Italian, Polish, German and Greek all have idioms that look similar to English ones but use different images. Only use an English idiom you have seen used in English.
Trap: Using old-fashioned idioms because they are in old textbooks: It's raining cats and dogs.
Fix: Many people still understand it, but it sounds dated and a bit forced. It's pouring (down) is more natural.
Trap: Using too many idioms in one answer to impress the examiner.
Fix: One natural idiom is enough. A long list of idioms sounds memorised and can make your answer less clear.
Trap: Using an idiom with the wrong meaning: I was over the moon when I failed my test.
Fix: Check the meaning and the feeling (positive, negative, neutral) of every idiom before using it.

Use it in the exam: Speaking Part 4

In Speaking Part 4, an idiom can make an opinion sound natural and lively, but it must fit the meaning exactly. The sample answer below uses two idioms, which is plenty for one answer. Notice that the rest of the answer uses clear, standard vocabulary. More questions are in our Part 4 question bank.

Sample Part 4 answer with idioms

Examiner: Do you think young people today have more pressure on them than in the past?

In some ways, yes. My parents say that when they were teenagers, the only pressure was passing exams, whereas now young people are also judged online all the time. Being popular on social media is easier said than done, and it can really affect your confidence. On the other hand, my grandparents had to start working at fifteen, which must have been an uphill struggle. So I'd say the pressure has changed rather than increased. Maybe every generation feels it has the hardest time.

Why it works

Uses only two idioms (easier said than done, an uphill struggle), both with the correct meaning.
The rest of the answer uses clear, neutral vocabulary, so the idioms stand out naturally.
Compares past and present with 'whereas' and 'On the other hand'.
Ends with a thoughtful conclusion rather than another idiom.

Idiom practice: questions to answer

Answer each question aloud in 30 to 45 seconds. Try to use one idiom from the tables above naturally, but only if it really fits.

Using idioms naturally

Tell me about something that was harder to learn than you expected.
When was the last time you felt really nervous? What happened?
What do you do to relax when you're stressed?
Have you ever had to make a decision at the last minute?
Is there anything you do only very rarely, but really enjoy?
Describe a time when you and a friend disagreed about something.
Is it worth paying a lot of money for a good experience, like a concert?
Tell me about a time someone went the extra mile to help you.

B2 idioms: FAQ

Should I use idioms in the B2 First exam?

Use a few in speaking and informal writing, where they sound natural, and only if you are sure of the form and meaning. Avoid them in essays and reports. Accurate everyday vocabulary is more important than idioms.

How many idioms do I need to know for B2?

There is no official number. Knowing a set of common idioms helps you understand natural English in listening and reading. For active use, a small group that you can use correctly is enough.

Are idioms tested in Reading and Use of English?

Fixed expressions and collocations are common in Part 1, and Part 4 transformations sometimes use a fixed phrase. Very colourful idioms are less common than expressions such as make up your mind or in the nick of time.

Is 'it's raining cats and dogs' a good idiom to use?

Most people will understand it, but it sounds old-fashioned and is rarely used in everyday conversation. It's pouring or It's pouring down is more natural.

What is the difference between an idiom and a phrasal verb?

A phrasal verb is a verb plus a particle (give up, get over). An idiom is any fixed expression whose meaning isn't obvious from its words (a piece of cake). Some phrasal verbs are idiomatic too. Practise phrasal verbs with our phrasal verb trainer.