The difference between then and than is fairly simple, but many people, including experienced English speakers, have difficulty with these two words. In fact, “than” and “then” are totally different parts of speech, used in entirely different ways; the confusion is probably linked to the fact that they sound very similar in spoken English, making it difficult to tell which word is being used. Knowing the difference between then and than will greatly improve the readability and quality of your written English.

The word “than” is a conjunction, which means that it links two clauses. This word is further classified as a subordinating conjunction, which means that it establishes some sort of relationship between two clauses. In the case of “than,” the relationship is comparative. For example, you could say that “this apple is bigger than the one I had last night,” or “was the sequel better or worse than the first movie?” Any time you are comparing two things, “than” is the appropriate word to use.

On the other hand, “then” is an adverb, meaning that it modifies a part of speech or a clause. Specifically, “then” is used as a conjunctive adverb to join two clauses which are separated by time; “then” acts like a unit of time in a sentence, telling you when something happened (or is going to happen). For example, one could say “he went to the store, and then stopped by the park,” or “please do your homework, and then you may watch television.” In both of these sentences, the word “then” could be replaced by “after that,” and the sentences would make sense.

If you're looking at a sentence and trying to figure out whether “then” or “than” is appropriate, think about what you are trying to convey with the sentence, and consider the difference between then and than. If you are comparing something, you want to use “than,” while if you are discussing the time at which something occurred, “then” is the most appropriate choice; remember, “then” rhymes with “when.” You can also use the “after that” trick, by replacing the word in question with “after that” and seeing if the sentence still makes sense. Using examples from above, “the apple is bigger after that the one I had last night” is rather nonsensical, while “please do your homework, and after that you may watch television” works as a sentence.

As you can see, the difference between then and than is far from subtle, and mastering it is crucial for people who want to be communicate clearly, effectively, and professionally. Fortunately, unlike the difference between “effect” and “affect,” the difference between then and than is quite easy to remember, making it easy to use these words correctly.