What is the Difference Between Than and Then?

Than and then are often mixed up in English, partly because they have similar spelling and sound alike. However, the words then and than have very different meanings and uses in language. Then is used in several different ways relating to the element of time. It is most commonly used as an adverb and, in some specific cases, as an adjective and noun. You need to apologize, and then you can come back in. Than is a preposition and conjunction, generally conveying a comparison. Billy liked the movie more than the book. Examples of using than and then:

I eat my breakfast and then I go to work.
I eat my breakfast, which I enjoy more than lunch.
If my car doesn’t start, then I will be in trouble.
If my car doesn’t start, I’ll take a bus rather than walk.
I am older than my brother, and after my birthday tomorrow, I will be even older then.

When to Use Then

Then usually has a relationship with time, typically acting as an adverb, modifying other adverbs as well as adjectives and, of course, verbs. Then can be defined in the dictionary in many ways including at that time, at the same time, in that case, soon afterward, in addition, next in order (in either place or time), or as a consequence. Here is on long, multi-layered example: My first class is English, then chemistry, then my favorite, history. In English, Mrs. DeLana told me, “If you enjoy poetry, then you should read Edgar Allan Poe. Then, when students are giving their reports, you could speak about him. There won’t be anyone else speaking about him then.” Here are some more examples of using then: Then can replace the words ‘at that time’ in a sentence and make grammatical sense:

You need to apologize first, and then you can come back in.
You need to apologize first, and at that time you can come back in.

Subsequently or afterwards. We use this when describing something that comes immediately after something else, either in time or in order:

Go up the stairs, then turn right.
It was pitch black, then a light shone in the distance.
When making scones, first combine the dry ingredients, then add the wet ones.
They argued and argued, then, finally, they came to a decision.

At that particular time. Here it is used in the past:

I was very pretty then.
Mrs. Williams, or Miss Jones as she was known back then, was the first to drive a car to school.
We lived in Philadelphia then, before the kids were born.

Here, then is used to describe a specific time, but one in the future:

Steven will drive to the game at 10am, if he can get everything prepared before then.
But by then, he may be exhausted.

As a consequence:

The police man pulled us over for speeding, then we got a ticket.
If you had kept your mouth shut, then we wouldn’t be in this mess.
I overslept so then I had to run to get there on time.

When to Use Than

Than is a conjunction and is always used to introduce a comparison, often with words like bigger, fewer, less, older and younger, so it would be bigger than, fewer than, and so forth. The use of than is highly specific and it is very difficult to replace it in a sentence with another word without changing the meaning.

I am older than my brother.
Paris is further away than Moscow
Carrots are healthier than hot dogs.

Examples of than in a sentence:

Helene is taller, prettier, and better dressed than her cousin, but her cousin is smarter than she is.
Kilimanjaro is bigger than Mont Blanc.
This old school had fewer students than the new one.
The Eiffel Tower is more iconic than the Empire State Building.
I would rather have been on vacation in Hawaii than working over the holidays in New Jersey.

While we mentioned that than is not easily replaceable in a sentence, it can be used in sentences that are don’t make direct comparisons. In these circumstances, than can be replaced in the sentence:

More than one billion people live in China. You could say: Over one billion people live in China.
John is older than You could say: John is over 50.
You can’t drink if you’re younger than 21. You could say: You can’t drink if you’re under 21.