“Than” is a subordinating conjunction that joins two clauses or sentences together in order to draw a comparison.

When “than” is used, implied words are often (correctly) left out of the subordinate clause. “I enjoy swimming more than running.” is the shortened version of the equally correct “I enjoy swimming more than I enjoy running.“
“Than” is used in the following cases.

1. To show a preference

• Mary would rather have a cat than a dog.
• I’d rather die than to see you suffer.

1. To show a lack of choice

• My car was so badly damaged in the accident that I had no choice other than to buy a new one.
• Martin has no friends other than Susan.

1. Used with a comparative (e.g. taller, smaller, smarter) and words like “more”, “less” and “fewer” to compare with time, quantity, or an object

• We need to reach the airport no later than 7 pm.
• 8 is larger than 3.
• John’s brother is taller than him.*

*Note: Some grammarians insist that the strictly correct usage here ought to be “he”. “Than” is not a preposition. It is a conjunction that links two sentences and leaves out some implied words. So “John’s brother is taller than he.” is the shortened version of “John’s brother is taller than he is tall.” However, in practice, it is incredibly rare for anyone to use the “he” construction.
Here are some common expressions that use “than”:

• “actions speak louder than words” – What someone does is more important than what they say.
• “better late than never” – It is better that something happens (late) than never at all.
• “better safe than sorry” – It is better to be careful than to regret any consequences.

“Then” is related to time and is used in the following cases:

1. To mean “at that time” (whether past, present, or future)

• Back then, life was so much simpler.
• Did someone knock just then? I thought I heard something.
• I’m free next Wednesday. Should we meet then?
• You’re thinking of waiting for Wendy? By then, we’d all be dead!

1. To mean “next”

• We had dinner, then we watched a movie.
• I worked all day, then treated myself to a well-deserved massage in the evening.

1. To mean “in that case” or “therefore”. This is often is an “if… then” construction.

• You think I’m annoying? Fine, I’ll stop trying to help you then!
• If you had listened to me, then you wouldn’t be in this sad situation.

Here are some common expressions that use “then”:

• “there and then” – Immediately. When Kevin suggested a round-the-world vacation to Lisa, she agreed there and then.
• You can also use “then-” to refer to a past status. At my first job, my then-boss (my boss at that time) was like a father to me.

A simple trick to remembering the difference is to think of “then” (with an e) being related to “time” or something happening “next”. Whereas “than” (with an a) is used for “comparison”.

Even if you meant the correct word, pronouncing it wrongly might still cause confusion. Learn the difference and practice pronouncing the words correctly.

Than [ðæn]. The vowel sound is made with the tongue almost flat near the bottom of the mouth.

Then [ðɛn] The vowel is made with the tongue at a very slightly higher position compared to "than".

Now that you know the difference, enjoy a meme that one of our students shared with us!

The "no sooner… than" expression is used to show that something happened immediately after the first event. Even though it seems like "then" would be the correct word here, you should instead use "than".

No sooner had the robber entered the bank than the police arrived.

No sooner had I entered the club than the music stopped.