The similar sounding words ‘then’ and than’ confuse many English speakers and if you find yourself using one for the other, please go through this article.
The word ‘than’ is used to show comparison and is a conjunction(A conjunction is a word that joins two sentences).

1. Adhir is smarter than Dinesh.
2. Homemade food is healthier than fast-food.
3. He is older than you.

On the other hand, the word ‘then’ is used either to show a sequence of events or a sense of time. Read the examples carefully to understand.

1. If you get full marks, then I will buy you a car.

2. Finish your homework and then we will go out for dinner.

3. I will reach home at night. I will call you then.

4. I will get free at 5. Can we meet then?

Notice how the first two sentences show a sequence of events and the next two show a sense of time. The speaker in sentence 3 and 4 is referring to particular time (‘at night’ and ‘at 5’).
Note:- When confused, think about what you’re trying to say/write. Only if you’re comparing will you use ‘than’, for every other situation, use ‘then’.