A child is younger than one year. His age is six months.

[tufguy]

A child is younger than one year. His age is six months.

Please check my sentences.

 

[GoesStation]

Was this some particular child?

 

[emsr2d2]

Why did you feel the need to explain that six months is less than one year?

 

[Tdol]

This is unnatural. He is six-months-old is natural.

 

[GoesStation]

He is six-months-old is natural.

I wouldn't use the hyphens.

 

[emsr2d2]

He's six months old.
He's a six-month-old.

 

[jutfrank]

I believe you're once again mixing up your own thoughts with the language used to express them. I can only imagine that your first sentence was meant to give us some explanation to the meaning of the second sentence.

Think about an actual sentence that you want to say to someone. Think about why you want to say it.

My best guess is that your post should have looked something like this:

If a child is younger than one year, is it correct to say the following sentence?:

His age is six months.

The blue part is the question that you want to ask and the red part is the sentence you're asking about. Can you understand that they are two very different things?