Using FOR and SINCE

Prepositions are small words that are related to another element of the sentence. They are essential because they provide additional details about the sentence by placing events, people, and objects in a place and time. We use the prepositions for and from to locate an event in a time frame and add information about its duration.

The prepositions for (para) and since (desde) have the same general purpose but have a different connotation . With them we always use the present perfect of the verb, when we refer to the present.

We use For when we measure duration, how long something lasts (when we say how long something lasts ).

For + a period of time

To measure a period of time up to the present, the present perfect and not the present is used in English:

• I have known her for a long time. (Correct) / La conozco desde hace mucho tiempo. (Correcto)
• I know her for a long time. (Incorrect) / La conozco desde hace mucho tiempo. (Incorrecto)
• I have lived here for ten years. (Correct) / He vivido aquí durante diez años. (Correcto)
• I live here for ten years. (Incorrect) / Vivo aquí desde hace diez años. (Incorrecto)

Present tense with For refers to a period of time that extends into the future.

• How long are you here for? (Until when) / ¿Por cuánto tiempo estás aquí? (Hasta cuando)
• How long have you been here for? (Since when) / ¿Cuanto tiempo has estado por aqui? (Desde cuando)

Uses of For

However, we don’t use For with expressions like all day or all the time.

• I was there all day. (Correct) / I was there all day. (Right)
• I was there for all day. (Incorrect) / I was there all day. (Incorrect)

Using SINCE

Since it gives the starting point of actions, events or states. It refers to when things started.

Since + a point in time (in the past), until now. / From + a point in time (in the past), until now.

• I’ve been waiting since 7 o’clock. / He estado esperando desde las 7 en punto.
• I have known him since January / Lo conozco desde enero.

With since (since) we use the present perfect or the past perfect .

• I have been here since 5 o’clock and I am getting tired. / Llevo aquí desde las 5 y me estoy cansando.
• I had been working since 5 o’clock and I was getting tired. / Llevaba trabajando desde las 5 y me estaba cansando.

Since it can also be used in the structure It has been + period of time + since (It has been + period of time + since).

• It has been two months since I last saw her / Han pasado dos meses desde la última vez que la vi.
• It has been three years since the last earthquake. / Han pasado tres años desde el último terremoto.

When is FOR used and when is SINCE?

Knowing when to use FOR and when to use SINCE is important. Therefore, it is useful to see a summary of the contrast between FOR and SINCE.

FOR To mention a specific period (or duration) of time SINCE FROM to mention the starting point of a period of time (continued so far).

• I have been a doctor for fifteen years. (duration = 15 years)I have been a doctor since 1992. (starting point = 1992) / Soy médico desde hace quince años. (duración = 15 años) Soy médico desde 1992 (punto de partida = 1992)
• She has been a mother for six months. She has been pregnant since her first child was born. / Ha sido madre durante seis meses. Está embarazada desde que nació su primer hijo.
• My sister has lived in Frankfurt for nine months.          My sister has lived in Frankfurt since the beginning of March. / Mi hermana vive en Frankfurt desde hace nueve meses. Mi hermana vive en Frankfurt desde principios de marzo.

Both For and Since are most commonly used with the perfect tense ; we do not use these expressions in the present tense.

Summary

For and since helps to locate an event in a period of time and adds information about its duration. They are always used with the present perfect, when referring to the present.

For is used to express the duration of a period that is still in progress. Because it is placed before periods of time. Since it is used to express the exact current or past starting point of an event. It is placed before the starting points.

For example:

• I’ve been a firefighter for 16 years He sido bombero durante 16 años”. = Usamos for (para) porque estamos expresando la duración de la acción.
• I’ve been a firefighter since 2000 “”Soy bombero desde 2000”. = Usamos since (desde) porque estamos expresando el punto de partida de la acción.

Remember! These are the next available calls for an official English exam.