When to Use a Hyphen in the Phrase “Year Old”?

If you’re wondering whether the phrase “year old” should have a hyphen or not, you’re not alone. Many people struggle with remembering how to write the phrase correctly, including native writers.

But don’t worry as we’re going to help you learn when and how to hyphenate the phrase so you can write without making this common mistake.

“Year Old” – To Hyphenate or Not?

The phrase “year old,” which indicates an age, should be hyphenated in specific situations that we’re going to explain. This means avoiding the hyphen in others.

“Year-old” – When to Use a Hyphen

Use a hyphen between “year” and “old” to form an adjective that modifies the following noun. So if there’s a noun after the phrase “year old,” make sure you hyphenate the phrase so it can describe the age of the noun, whether that’s a person, object, or place.

Examples:

My 20-year-old son is a math genius.

I have a two-year-old cat and a three-year-old dog that always play together.

As you can see, the hyphenated phrase in the first example tells the age of “my son,” and the hyphenated phrases in the second example reveal the ages of the cat and the dog. The three “year-old” phrases are followed by nouns – son, cat, and dog.

Another situation when you should also use a hyphen is when you use the “year-old” phrase as a noun.

Example:

He is just an 18-year-old, and he is already a successful businessman.

“Year Old” – When to Avoid the Hyphen

You shouldn’t use a hyphen when there’s no noun following the phrase “year old.” The noun is before the phrase, so “year old” usually ends the sentence or the clause.

Examples:

The museum is 50 years old.

My grandfather is 80 years old, but he still loves dancing.

In both examples, the phrase “years old” modifies the nouns “museum” and “grandfather,” which come before and not after the phrase.

Long Story Short

Proper hyphenation of “year old” requires remembering three simple rules. The first one is using a hyphen to form the adjective “year-old” which will describe the age of the following noun.

The second rule is using a hyphen when using the phrase as a noun. And the third one is avoiding the hyphen when the phrase modifies a noun that precedes it.

Video examples: