One Third or One-Third? Which is Correct? Simple Grammar Guide

Many people get confused about how to write fractions correctly. One common question is about one third. The one third meaning is a part of something divided into three equal parts. Knowing when to hyphenate can make your writing clear.

You write one third without a hyphen when it stands alone in a sentence. For example, “He ate one third of the cake.” Here, one third meaning shows a portion, not describing any other word, so no hyphen is needed.

Use one-third with a hyphen when it describes a noun directly, like “a one-third share.” The one third meaning stays the same, but the hyphen helps readers understand that the words work together as a single descriptive term.

Table of Contents

One Third or One-Third? Which is Correct?

The terms one third and one-third both refer to a fraction, but their use depends on the sentence. One third acts as a noun phrase, while one-third works as a compound adjective describing a noun.

Example of One Third:
“I ate one third of the chocolate cake.”
Here, one third shows a fraction of a whole without directly describing a noun.

Example of One-Third:
“She received a one-third share of the inheritance.”
In this case, one-third is a hyphenated fraction modifying the noun share, making the meaning clear.

Quick Rule of Thumb:

Hyphenate when preceding a noun: one-third slice
No hyphen when standing alone or after a noun: I ate one third

One Third: When To Use?

You use one third without a hyphen when it acts as a noun phrase in a sentence. It usually shows a fraction of a whole and does not directly describe a noun.

It works well as the subject or object of a verb. This makes your sentence clear and easy to read, showing the one third meaning without confusion for readers.

Examples:

“One third of the cake was left after the party.”
“I’ll take one third of the pizza, please.”

In these sentences, one third stands alone as a fraction, not modifying any noun. This keeps the meaning clear and avoids the need for a hyphen.

One-Third: When To Use?

Use one-third with a hyphen when the fraction directly modifies a noun. It acts as a compound adjective and clearly shows that the two words work together to describe something specific.

This helps readers quickly understand your meaning. Without a hyphen, the sentence could be confusing. One-third ensures clarity and shows the fraction as a descriptive term, making your writing precise and professional.

Examples:

“She inherited a one-third interest in the family business.”
“The team completed a one-third segment of the project ahead of schedule.”

In these examples, one-third modifies nouns like interest and segment, giving a clear picture of the portion. The hyphen connects the words as a single descriptive unit.

It also prevents misreading the sentence. Without a hyphen, readers might pause or misunderstand the fraction meaning, which can make the sentence unclear or awkward.

Always hyphenate fractions when they describe a noun directly, like one-third share. Use plain one third when it stands alone, such as “I ate one third of the pie.” This keeps writing clear.

Examples of Using “One Third“ in A Sentence

One third of the students in the class are studying science.
I donated one third of my earnings to charity.
One third of the cake was left after the party.
He spent one third of his savings on a new laptop.
One third of the committee disagreed with the proposal.
She drank one third of the water before lunch.
One third of the tickets were sold within the first hour.

Examples of Using “One-Third“ in A Sentence

She inherited a one-third interest in the family business.
The contractor completed a one-third segment of the construction ahead of schedule.
The new law was passed with a one-third majority vote in the senate.
Each partner contributed a one-third stake in the joint venture.
The recipe called for a one-third cup of sugar to be added to the mixture.
He owns a one-third share of the company with his two siblings.
The project budget was reduced by a one-third portion due to cost cuts.

Conclusion

In conclusion, understanding the difference between one third and one-third makes your writing clear and precise. Use one third without a hyphen when it stands alone as a noun phrase showing a fraction of a whole. Use one-third with a hyphen when it directly modifies a noun as a compound adjective, like a one-third share.

Following these rules prevents confusion and improves sentence clarity. Remember the quick rule of thumb: hyphenate before nouns, don’t hyphenate when standing alone. Mastering these simple guidelines ensures accurate writing and correct use of fractions in English.