The Difference between Por vs Para

In Spanish, both por and para are translated into English as "for", but they have different usages in Spanish. Instead of thinking about the words that we use when trying to decide if it is por or para, you should think about the meaning of the sentence.
 
The situations that you use Por in:

1. Motion of general location
   
2. Duration of an action
   
3. Reason or motive for an action
   
4. Object of a search
   
5. Means by which
   
6. Buy or exchange
   
7. Unit of measure
   
8. Agent (passive voice
   

The situations that you use Para in:

1. Destination
   
2. Deadline
   
3. Purpose infinitive
   
4. Recipient
   
5. Comparison with others on an opinion
   
6. Employment
   

You can also tell which it is from these common phrases that are used with por and para.

Expressions with Para:

1. no estar para bromas - to be in no mood for jokes
   
2. no ser para tanto - to not be so important
   
3. para colmo - to top it all off
   
4. para que sepas - just so you know
   
5. para siempre - forever
   

Expressions with Por:

1. por ahora - for the time being 
   
2. por allí/aquí - around there/here 
   
3. por casualidad - by chance/accident 
   
4. por cierto - by the way 
   
5. por ejemplo - for example 
   
6. por eso - therefore; for that reason 
   
7. por fin - finally 
   
8. por lo general - in general 
   
9. por lo menos - at least 
   
10. por lo tanto - therefore 
    
11. por lo visto - apparently  
    
12. por más/mucho que - no matter how much 
    
13. por otro lado/otra parte - on the other hand 
    
14. por primera vez - for the first time 
    
15. por si acaso - just in case 
    
16. por supuesto - of course