Present Perfect: For vs. Since

Imagine a bridge. One side is the past. The other side is right now. The Present Perfect is that bridge. When we use for and since, we are looking at that bridge. We want to know the length of the bridge. Or we want to know where the bridge starts. For measures the total length of time. It is like a ruler. You use it to count minutes, hours, or years. Since points to a specific moment. It is like a pin on a map. It tells us exactly when the action began. Most languages have different ways to say this. In English, we are very picky about these two words. If you use the wrong one, people will still understand you. However, using them correctly shows you are a pro. It is like wearing matching socks. It just feels right.

1. 1To use for and since, you need the Present Perfect first. Here is how you build it:
2. 2Start with your subject like I, You, He, or She.
3. 3Add the helping verb have or has.
4. 4Use have for I, you, we, and they.
5. 5Use has for he, she, and it.
6. 6Add the past participle of your main verb. For example, lived, worked, or known.
7. 7Finally, add your time marker with for or since.
8. 8Example with for: I have lived here for five years.
9. 9Example with since: I have lived here since 2018.

Use for when you talk about a duration. This is a quantity of time. You can count it on your fingers. Use it for ten minutes, two weeks, or six months. It also works for vague times like a long time or ages. Use it in a job interview. You might say, I have worked in sales for three years. This shows your experience clearly. Use it when ordering food. I have waited for my pizza for twenty minutes! This tells the waiter you are hungry.

Use since when you talk about a starting point. This is a specific date or time. Use it for Monday, 9:00 AM, or January. It also works with life events. You can say since I was a child or since I graduated. Use it when meeting new people. I have lived in London since last summer. This gives them a clear timeline of your life. It helps people understand your story better.

Do not use for or since with the Past Simple. This is a very common trap. You cannot say I lived here since 2010. That sounds like you moved away already. If you are still there, use the Present Perfect. Also, do not use since with a duration. Saying since five hours will make a native speaker's brain itch. It just doesn't fit.

Avoid using for with the word all. You don't say for all day. You just say all day. For example, I have been busy all day. Adding for there is like putting ketchup on pancakes. It is just too much. Finally, don't use since for future events. It is only for things that have already started. If you start a job tomorrow, you can't use since yet. Wait until you actually start! Even native speakers mess this up sometimes, so don't sweat it too much.

One big mistake is using since with a number of years. Many people say since three years. This is incorrect. You must say for three years. Remember: for is for counting. Since is for naming the start. Another mistake is forgetting the have or has. You cannot say I lived here for a year if you still live there. That means you left!

People also confuse for and during. During tells us when something happened within a block of time. For tells us how long it lasted. If you say I slept during the movie, that is fine. If you say I slept for two hours, that is the duration. Using them correctly keeps your stories clear. Think of it like a recipe. If you swap salt for sugar, the cake tastes weird. Grammar is the same way!

How is this different from the Past Simple? The Past Simple is for finished actions. I lived in Paris for a year means you are not in Paris now. I have lived in Paris for a year means you are still eating croissants every morning.

What about ago? We use ago with the Past Simple. It counts back from now. I moved here two years ago. This is a finished fact. I have been here for two years is a continuing state. See the difference? One is a dead end. The other is a moving path. Choosing the right one changes the whole meaning of your sentence. It is like choosing between a photo and a live video.