Year old vs. Year-old

Do you know when to hyphenate the words “year old”?

The Takeaway

If you are using “year old” as an adjective, then you need to put a hyphen between the words. For example, you would write “the two-year-old child.” “Two-year-old” is an adjective that describes the child. 

Hyphenating Year Old

You put a hyphen with “year old” if it modifies the noun that follows it. So, if the phrase tells the age of a person, place, or thing, then it should be written as “year-old.” This adjective will also go before the noun in the sentence. 

You will also put a hyphen between year old and the number that comes before it. For example, “35-year-old adult” is written correctly. 

For example:

  • The 50-year-old bottle of wine was worth a lot of money.
  • The seven-year-old was happy to go to school.
  • His 12-year-old brother collects baseball cards.
  • Their 3-year-old niece is visiting tomorrow.
  • Her six-year-old dog is really hyper.

Sometimes age is used as a noun. Year old is also hyphenated in these sentences.

For example:

  • The 50-year-old was driving the car.
  • For being a 95-year-old, she’s still very sharp.

When You Don’t Hyphenate Year Old

If year old comes after the noun it modifies, it should not be hyphenated.

For example:

  • This car is 3 years old.
  • She was 42 years old when she got married.
  • Her mother just turned 83 years old.
  • This book is 104 years old.
  • This country is hundreds of years old.

Related: Are Numbers Hyphenated When Written Out?


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