For vs Since: How to Talk About Time in English (Without Getting the Tense Wrong)

“I live here since three years.” “I know him since a long time.” If either of those sounds almost right to you, you’re not alone — for and since trip up learners from almost every language background, and not just because the words are different. The real problem is that getting them wrong usually drags a verb tense down with it.

Good news: there’s a genuinely simple test that fixes 90% of the confusion in one second flat.

The one-second test: duration or starting point?

Look at the word or phrase that comes right after for or since. That’s all you need.

For + a length of time (how long something lasts):

• for three years
• for a while
• for ages
• for twenty minutes

Since + a fixed point in time (when something started):

• since 2020
• since Monday
• since I moved to Madrid
• since I was a kid

If you can answer the question “how long?” with that phrase, use for. If you can only answer “since when?”, use since. “Three years” answers how long; “2020” answers since when. That’s the whole test.

The tense trap: why this breaks more than vocabulary

Here’s the part that actually causes most of the visible mistakes. Both for and since, when they’re talking about something that started in the past and is still true now, need the present perfect — not the present simple.

❌ “I know her since 2019.”
✅ “I have known her since 2019.”

❌ “I live in Valencia for six years.”
✅ “I have lived in Valencia for six years.”

Why does this happen so often? In Spanish, French, Italian and plenty of other languages, the equivalent idea is expressed with the present tense plus a time word (vivo aquí desde hace seis años) — so the translation in your head reaches for the English present simple too. English just doesn’t work that way: if the action is still going on, the verb has to show that connection between past and present, and that’s exactly what the present perfect does.

For actions you can picture actually happening over that stretch of time (not just existing, but doing something continuously), swap in the present perfect continuous instead:

• “It has been raining since Tuesday.”
• “She has been studying English for three months.”
• “We‘ve been waiting for twenty minutes.”

Both tenses are correct — present perfect simple for states and general facts (have known, have lived, have had), present perfect continuous for actions in progress (have been studying, have been waiting). What’s never correct with this meaning is the plain present simple.

Side by side

• I’ve worked here for eight months. / I’ve worked here since March.
• She’s been married for a decade. / She’s been married since 2016.
• We haven’t spoken for ages. / We haven’t spoken since the wedding.
• He’s lived abroad for most of his life. / He’s lived abroad since he was eighteen.

One more job for “since”

Since has a second, completely unrelated meaning: “because.” “Since it’s raining, let’s stay in” has nothing to do with time at all — it’s just a slightly more formal way to say “because.” This doesn’t affect the duration rule above, but it’s worth knowing so a sentence like that doesn’t throw you off when you meet it.

Quick self-check

Fill the gap with for or since, then check the tense too:

1. I ___ have been learning Spanish ___ 2023. (since — have been learning is already correct)
2. They’ve lived in that flat ___ three years. (for)
3. We haven’t seen each other ___ her graduation. (since)
4. He’s been working on the project ___ a few weeks. (for)

If you got all four without pausing, the test has already clicked — now it’s just a matter of using it automatically, under pressure, in real conversation. That’s the part a textbook can’t give you, but a short exchange with a real person can. If you want to test where your English actually stands right now, Parlazo’s free level test takes a few minutes, and a one-on-one lesson with a native teacher is the fastest way to turn “I understand the rule” into “I just say it correctly without thinking.”