When you want to ask about the age of a person or thing, you use How old and the verb be.

'How old are you?' – 'Thirteen.'

'How old is he?' – 'About sixty-five.'

'How old's your house?' – 'I think it was built about 1950.'

There are several ways in which you can say how old someone or something is. You can be exact, or you can be less precise and show their approximate age.

When you want to say how old someone is, you use the verb be followed by a number.

I was nineteen, and he was twenty-one.

I'm only 63.

You can put years old after the number if you want to be more emphatic.

She is twenty-five years old.

You can also put years of age after the number, but this is more formal and is more usual in written English.

He is 28 years of age.

Don't use 'have' to talk about age. For example, don't say 'He has thirteen years'. You say 'He is thirteen' or 'He is thirteen years old'.

When you are mentioning someone, you can show their exact age using of or aged, or, in American English, age after the noun that refers to them, followed by a number.

...a man of thirty.

...two little boys aged nine and eleven.

They have twin daughters, age 18.

You can also mention someone's age using a compound adjective in front of a noun. For example, you can refer to a five-year-old boy. Note that the noun referring to the period of time, such as year, is always singular, even though it comes after a number. The compound adjective is usually hyphenated.

...a twenty-two-year-old student.

...a five-month-old baby.

You can also refer to someone using a compound noun such as ten-year-old.

All the six-year-olds are taught by one teacher.

...Melvin Kalkhoven, a tall, thin thirty-five-year-old.

If you are not sure exactly how old someone is, or you do not want to state their exact age, you can use the verb be followed by about, almost, nearly, over, or under, and a number.

I think he's about 60.

He must be nearly thirty.

She was only a little over forty years old.

There weren't enough people who were under 25.

You can also use a number with the suffix '-ish' to give an approximate age.

The nurse was fiftyish.

You can also use above the age of or below the age of followed by a number. This is more formal.

55 percent of them were below the age of twenty-one.

You can show that someone's age is between 20 and 29 by saying 'He's in his twenties' or 'She's in her twenties'. You can use thirties, forties, and so on in the same way. People aged 13 to 19 are said to be in their teens.

Note that you use in and a possessive determiner in these structures.

He was in his sixties.

...when I was in my teens.

Another way of showing approximate age is to use something after a number that ends in zero.

A table of thirty-something guys.

She was twenty-something.

You can use early, mid-, middle, or late to show approximately where someone's age comes in a particular ten-year period (or eight-year period in the case of 'teens').

Jane is only in her early forties.

She was in her mid-twenties.

He was then in his late seventies.

You can put most of the above structures after a noun such as man or woman to show someone's approximate age.

They provide help for ladies over 65.

She had four children under the age of five.

...a woman in her early thirties.

Don't use about, almost, or nearly immediately after a noun. For example, don't say 'He is a man about 60'. Say 'He is a man of about 60'.

In British English, you can refer to a group of people whose age is more or less than a particular number using a compound noun which consists of over or under followed by the plural form of the number. This usage is understood but not used in American English.

The over-sixties do not want to be turned out of their homes.

Schooling for the under-fives should be expanded.

If you want to show that someone's age is similar to someone else's, you can use the verb be followed by expressions such as my age, his own age, and her parents' age.

I wasn't allowed to do that when I was her age.

He guessed the policeman was about his own age.

To show the age of a person you are mentioning, you can use these expressions after the noun which refers to the person, or after the noun and of.

I know a bit more literature than most girls my age.

It's easy to make friends because you're with people of your own age.

There are several ways of showing how old someone was when something happened.

You can use a clause beginning with when.

I left school when I was thirteen.

Even when I was a child I was frightened of her.

You can use at the age of or at, followed by a number showing the person's age.

She had finished college at the age of 20.

All they want to do is leave school at sixteen and get a job.

Aged followed by a number is also used, mainly in writing, especially when talking about someone's death.

Her husband died three days ago, aged only forty-five.

As is used with a noun phrase such as a girl or a young man to show that someone did something when they were young. This structure occurs mainly in writing.

She suffered from bronchitis as a child.

As teenagers we used to stroll round London during lunchtime.

If you want to show that someone does something before they reach a particular age, you can say that they do it, for example, before the age of four or by the age of four.

He maintained that children are not ready to read before the age of six.

It set out the things he wanted to achieve by the age of 31.

If you want to show that someone does something after they reach a particular age, you can say that they do it, for example, after the age of four.

After the age of five, your child will be at school full time.

If you want to say how old something is, you use the verb be followed by a number, followed by years old.

Most of the coral is some 2 million years old.

The house was about thirty years old.

You can't just use 'be' and a number, as you can when stating the age of a person. Don't say, for example, 'The house was about thirty'.

The usual way of showing the age of something you are mentioning is to use a compound adjective in front of the noun referring to it. For example, you can refer to a thirty-year-old house. As with compound adjectives showing the age of a person, the noun year is always singular and the adjective is usually hyphenated.

...a rattling, ten-year-old car.

...a violation of a six-year-old agreement.

You can also use a number, especially a large number, and years old after a noun referring to a thing.

They found rocks 200 million years old.

You can show the approximate age of something by using an adjective that shows the period in history in which it existed or was made.

...a splendid Victorian building.

...a medieval castle.

You can show the century when something existed or was made by using a modifier consisting of an ordinal number and century.

...a sixth-century church.

...life in fifth-century Athens.