You wrote “I have lived here since three years” and your teacher circled it in red. You changed it to “for three years” and got it right the next time, but you still can’t explain why. That gap between knowing the rule and applying it under pressure is exactly what trips learners up on since and for.
The rule itself is simple, but most explanations stop at the definition and never give you enough real practice to make the choice automatic. This article gives you both: the actual rule, why the mistake happens in the first place, and enough exercises to fix it for good.
Table of Contents
The Rule Behind Since vs For
Both words connect a present perfect verb to a period of time, but they answer different questions. Since answers “when did it start?” and is followed by a point in time. For answers “how long?” and is followed by a duration. Once you separate those two questions in your head, the choice stops being a guess.
| Word | Answers | Examples |
|---|---|---|
| Since | A starting point in time | since 2019, since Monday, since I moved here, since 9am |
| For | A length or duration of time | for five years, for two weeks, for a long time, for ages |
Why This Mistake Keeps Happening
In many languages, one single word covers both meanings, so your brain doesn’t naturally split “starting point” from “duration” the way English requires. The fastest fix is a quick mental test: if you can put a specific date, day, or moment after the word, use since. If you can put a number of hours, days, months, or years after it, use for. “Since Monday” works because Monday is a point in time. “For Monday” doesn’t work, because Monday isn’t a length of time.
Since vs For in Real Sentences
- I have worked here since 2020. — 2020 is a starting point.
- I have worked here for five years. — five years is a duration.
- She hasn’t called since last week. — last week is a point in time.
- She hasn’t called for a week. — a week is a length of time.
- They’ve been married since 2015.
- They’ve been married for nine years.
A Trap That Catches Advanced Learners Too
“Since” can also mean “because” (“Since you’re here, let’s start”), which has nothing to do with time at all. This second meaning is common in spoken and written English, so don’t assume every “since” is about duration — check whether the sentence is talking about time or giving a reason.
5 Mistakes With Since and For
| Instead of this | Say this | Why |
|---|---|---|
| “I have lived here since three years” | “I have lived here for three years” | Three years is a duration, not a starting point |
| “I haven’t seen him for 2020” | “I haven’t seen him since 2020” | 2020 is a specific point in time |
| “Since a long time” | “For a long time” | “A long time” is a duration, not a starting point |
| Using past simple instead of present perfect | “I have known her since 2018” (not “I know her since 2018”) | Since/for with an ongoing action normally needs present perfect |
| “Since two hours” | “For two hours” | “Two hours” is a length of time, not a starting point |
Practice: Test Yourself
Choose Since or For
1. I’ve been waiting ___ two hours.
2. She has worked at the company ___ 2017.
3. We haven’t spoken ___ last summer.
4. He has played the guitar ___ he was seven.
5. They’ve lived in Madrid ___ six months.
6. I haven’t eaten ___ this morning.
7. She has been studying English ___ three years.
8. We’ve known each other ___ university.
Correct the Mistake
- “I have lived here since ten years.”
- “She hasn’t called for last week.”
- “I know him since 2015.”
Speaking Challenge
Say three true sentences about yourself out loud, one with since, one with for, and one using since to mean “because.” If you want a tutor to correct your grammar in real conversation instead of on paper, you can practice this live in a Free Lesson.
Answer Key
- Fill in the blanks: 1-for, 2-since, 3-since, 4-since, 5-for, 6-since, 7-for, 8-since
- Correction 1: “I have lived here for ten years.”
- Correction 2: “She hasn’t called since last week.”
- Correction 3: “I have known him since 2015.”
Want This to Become Automatic?
Rules like this one stop being a conscious decision once you’ve used them in real conversation enough times. Our English grammar courses build exactly this kind of fluency through practice, not memorization. If you want a tutor to catch these small slips in real time, you can start with a private English tutor or book a Free Lesson to see how it works.
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Frequently Asked Questions About Since vs For
What’s the simplest way to remember since vs for?
Since answers “when did it start?” and takes a point in time. For answers “how long?” and takes a duration. If you can say “a number of + time unit” after it, use for.
Do since and for always need present perfect?
When describing an action that started in the past and continues now, yes: “I have lived here since 2018,” not “I live here since 2018.” Other tenses are possible in different contexts, but this is the pattern learners get wrong most often.
Can “since” mean something other than time?
Yes. “Since” can also mean “because”: “Since you’re already here, let’s get started.” Check whether the sentence is about time or giving a reason before choosing.
Why do I keep making mistakes with since and for even at an advanced level?
Many languages use one word for both concepts, so the split between “starting point” and “duration” isn’t automatic. It becomes automatic only through repeated, corrected practice, not from reading the rule once.
Is “for” ever followed by a specific date?
No. “For” is always followed by a length of time (for two years, for a while), never a specific point like a date or day.
Is “since” ever followed by a number of years?
Not directly. “Since” needs a starting point, so “since five years” is incorrect; it should be either “for five years” or “since [a specific year].”
What’s a quick test to check if I’m using since vs for correctly?
Ask yourself: does the word after it answer “when did this start” or “how long has this lasted”? The first needs since, the second needs for.
Does British English use since and for differently than American English?
No, the core rule is the same in both. The main variation is that American English sometimes uses simple past where British English prefers present perfect, but the since/for distinction itself doesn’t change.
How can I practice since vs for beyond exercises on a page?
Talk about your own life out loud using both words in real sentences, ideally with a tutor who can correct you immediately, since that immediate correction is what makes the rule stick.
What other grammar points are commonly confused alongside since and for?
During vs while, ago vs before, and until vs by are the next most common time-word confusions learners run into after mastering since and for.
