Principal vs. Principle: What’s the Difference?

Principal and principle are another set of homophones, which, despite sounding identical in their pronunciation, have completely different meanings.

They are among the ranks of to, too, and two, there, their, and they’re, and countless other confusing words in English. But as is the case with these other examples, once you know the difference, they are easy to tell apart.

What is the Difference Between Principal and Principle?

Today, we’ll discuss the differences between these two words and also give you a few tricks to remember the difference between principal vs. principle. After reading this post, you shouldn’t ever be confused when choosing principal or principle again.

When to Use Principal

Principal is both a noun and an adjective with a few different uses.

Difference in principal versus principleAs a noun, “principal” has a few different meanings. The most common meaning is used to refer to a person of high authority or prominence, someone who holds or plays an important role. An example of this would be a school principal.

  • Mr. Babcock is the principal of the high school.

Principal also has specialized meanings in finance and law. In finance, “principal” refers to a loan amount requiring repayment. In law, “principal” refers to a person having prime responsibility for an obligation or the main actor in the perpetration of a crime. A few examples,

  • How much have you repaid on the principal of your loan?
  • He was the principal in this crime, acting alone.

As an adjective, “principal” has the sense of “chief,” “leading” or “primary.” For example,

  • The principal cause of World War 2 was Hitler’s invasion of Poland.

In this sentence “principal” is modifying the word “cause,” saying that Hitler’s invasion of Poland the primary or chief reason for the start of World War 2.

When to Use Principle

define principal v principle grammar rulesPrinciple is only a noun and generally refers to a natural, moral, legal rule or standard. For example,

  • The principle of free speech is something that Americans take for granted.
  • You are a man of principle.

There are a few popular phrases that use the word “principle,” so while using these phrases, be sure not to accidentally use “principal.”

  • In principle, I agree with you.
  • On principle, I agree with you.
  • As a matter of principle, I must take a stand.

All three of these popular phrases use the word “principle” exclusively.

Remember the Difference

A great way to remember the differences between principle versus principal is found in the last three letters of each word.

Someone who is a “princi-P-A-L” should be looked at as your “pal.” Only people can be “pals” and principal refers to people, whereas “princi-P-L-E” refers to truths, rules, or standards. A truth or standard cannot be your “pal.”

You can also remember the mnemonic, “The principal has his principles.”

Another good mnemonic is, “The principal rule is that you stand by your principles and next to your principal.”


These two words have very different meanings, so when selecting principle or principal to include in your sentence, be sure it’s the correct choice.

Principal is a noun and adjective with specialized meanings in finance and law but most commonly used to refer to someone in a position of authority or high prominence.

Principle is only a noun and refers to a natural, moral, legal rule or standard.

You can remember the differences between these two words by remembering that princiPALs are people and they are your pals. PrinciPLEs are rules or standards and they cannot be your pal.