Prepositions:  The por / para Distinction
  Por and para are two common prepositions that are not generally interchangeable. They do not have English equivalents that consistently distinguish them. Below are rules for the use of each, with examples.
  1. Inexact location in time or space:
    • Trabajamos por la mañana.
      • We work in the morning.
    • Por allí hay unos libros.
      • There are some books over there.
    • Pensamos viajar por el este del país.
      • We intend to travel through (around) the country.
    • Por aquellos días había menos de cien habitantes.
      • In those days, there were fewer than 100 inhabitants.
  2. During a period of time (often omitted):
    • Tengo que trabajar (por) cuatro horas hoy.
      • I have to work for four hours today.
  3. In exchange for, as a substitute for:
    • Te doy diez dólares por esa corbata.
      • I'll give you ten dollars for that necktie.
    • Estoy enfermo. ¿Puedes dar la clase por mí?
      • I'm sick.  Can you teach the class for me?
  4. Per, at the rate of :
    • Trabajo cuarenta horas por semana.
      • I work forty hours per week.
  5. Due to, because of, as punishment for:
    • ¿Por qué no vas con ellas?
      • Why aren't you going with them?
    • Riñen a Natalia por llegar tarde.
      • They scold Natalia for arriving late.
    • No tengo coche.  Por esa razón, tomo el autobús.  I don't have a car.
      • For that reason, I take the bus.
    • Por ser extranjero, yo sé muy poco de esta cultura.
      • Because I'm a foreigner, I know very little about this culture.
  6. In support of, in favor of, for the sake of:
    • ¿Por quién piensas votar?
      • For whom do you intend to vote?
    • Estamos por cancelar el partido.
      • We are for (in favor of) canceling the game.
    • Rezan por las víctimas de la hambruna.
      • They pray for the victims of the famine.
  7. By means of, through:
    • Vamos por tren.
      • We go by train.
    • Pasa por esa puerta.
      • Come through this door.
  8. After ir, venir, enviar, etc. before the object of an errand:
    • Héctor, ve por leche, por favor.
      • Hector, go for (go get) milk, please.
    • Vine por ti.
      • I came for you (to pick you up).
  9. Judging from...:
    • A juzgar por lo que tú has dicho... 
      • Judging from what you've told me...
    • Por lo visto es así.
      • Apparently (it appears that) that is so.
  10. Before infinitive, meaning yet to be done (sin is sometimes used instead):
    • Hay mucho trabajo por hacer.
      • There's a lot of work to do.
  11. By, referring to agency, authorship:
    • El amor en los tiempos del cólera, por Gabriel García Márquez.
      • Love in the Time of Cholera, by Gabriel García Márquez
    • Esas reglas fueron establecidas por el comité.
      • Those rules were established by the committee.
  12. In concessive construction (no matter how...):
    • Lo tienes que hacer, por desagradable que sea.
      • You have to do it, no matter how disagreeable it may be.
    • No los escuches, por mucho que se quejen.
      • Don't listen to them, however much they complain.
  13. In multiplication operations, dimensions (by, times):
    • 7 por 5 son 35. 
      • 7 times 5 is 35.
    • El cuarto mide 13 por 10.
      • The room measures 13 by 10.
  14. After certain verbs; some examples:
    • Acabar por (to wind up ___ing):  Acabó por aceptar (acabó aceptando) la teoría. 
      • We wound up accepting the theory.
    • Mirar por  (to look out for):  Hay que mirar por tus amigos.
      • You have to look out for your friends.
    • Optar por  (to opt for, choose to):  Optamos por quedarnos en casa.
      • We chose to stay at home.
    • Preguntar por (to ask/inquire about):  No me preguntes por cosas así.
      • Don't ask me about things like that.
    • Tomar por (to take one for): No me tomes por enemigo.
      • Don't take me for an enemy.
    • Note:  No preposition is used after buscar, pedir to mean look / ask for:
      • Buscan sus maletas.  They are looking for their backpacks.
      • Le voy a pedir un lápiz.  I'm going to ask him for a pencil.
  15. In numerous idiomatic expressions; examples:
    • por ahora (for now); ¡Por Dios! (My goodness!); por esto, por eso (therefore); por escrito (in writing); por favor (please); por fin (finally); por lo menos (at least); por supuesto (of course)
  1. Goal, purpose, function:
    • Fui a España para aprender español.
      • I went to Spain to learn Spanish.
    • Es una botella para vino.
      • It's a wine bottle (bottle designed for wine)..
    • ¿Para qué sirve este chisme? 
      • What's this gadget for?
  2. Suitability, congruity (Considering that...):
    • Para extranjero, habla muy bien la lengua.
      • For a foreigner, he speaks the language very well.
    • Para lo buena que es la comida, ese restaurante cobra muy poco.
      • Considering how good the food it, that restaurant charges very little.
  3. Destination, object, beneficiary, etc.:
    • Estos regalos son para mis primos.
      • These presents are for my cousins.
    • Salimos para la Argentina el viernes.
      • We are leaving for Argentina on Friday.
    • Vamos a dejar eso para la próxima reunión.
      • Let's leave that for the next meeting.
    • ¿Para qué compañía trabajas?
      • What company do you work for?
    • Tenemos cuartos para seis personas, y comida suficiente para una semana.
      • We have rooms for six persons, and enough food for a week.
  4. From (one's) perspective; to (one's) (dis)advantage:
    • Para Luisa, eso no es nada difícil.
      • For Luisa, that's not hard at all.
    • Esa no es la mejor solución para nosotros.
      • That's not the best solution for us.
  5. With estar (to be about to...) (in Latin American, por is used instead):
    • Estamos para salir.
      • We're about to leave.
  6. By (a deadline):
    • Entreguen Uds. el informe para el día tres de febrero.
      • Turn the report in by February 3.