Spanish Prepositions - por vs. para

The prepositions por and para tend to be troublesome for non-native Spanish speakers. In some cases this is due to the fact that each of them is sometimes equivalent to the English preposition for. In other cases the difficulty comes from the diverse uses that each one has.

To express the idea of "in my opinion"

Para mí, el carro verde es mejor. - In my opinion, the green car is better.
Para Luis, el rojo es el máximo. - In Luis's opinion, the red one is the best.

To indicate the place toward which someone is going

Voy para Oaxaca. - I am going to Oaxaca.
Salimos para la tienda a las doce. - We left for the store at twelve.

To convey the time limit of a particular action

Tendrás que terminar para lunes. - You'll have to finish by Monday.
Quiero las fotos para las tres. - I want the pictures by three.

Para + Infinitive: "In order to" and the expression of purpose

Para sacar buenas notas hay que estudiar. - To get good grades you have to study.
Estos zapatos son buenos para bailar. - These shoes are good for dancing.

To express suitability

Los vestidos son para las mujeres. - Dresses are for women.
Este tornillo es para mi bicicleta. - This screw is for my bike.

To express the reason or motive for an action

Lo hice por tí. - I did it for you.
Cancelaron el partido por la lluvia. - They cancelled the game because of the rain.
Austin es conocido por su música. - Austin is known for its music.

To indicate a place where movement is occurring

Los ladrones entraron por la ventana. - The burglars came in through the window.
Vamos por la calle sexta. - We're going by way of Sixth Street.

Periods of time: parts of the day

por la mañana - in the morning
por la tarde - in the afternoon
por la noche - in the evening
por la noche - at night
por la madrugada - in the early morning

Por = per

Estoy contigo cien por ciento. - I'm with you one hundred percent.
Íbamos a 80 millas por hora. - We were going 80 miles per hour.
Gano diez dólares por hora. - I make ten dollars per hour.

To express price or an exchange

Te doy mi reloj por tu bici. - I'll give you my watch for your bike.
Lo compré por quince dólares. - I bought it for fifteen dollars.

Por + means of transportation

Vine por avión. - I came by plane.
Fuimos a Veracruz por autobús. - We went to Veracruz by bus.

Por = by

Esa canción fue escrita por Tracy Chapman. - That song was written by Tracy Chapman.