The verb to know · Conjugation
Present Perfect of know
The answer: have / has known
B1
A past action with a link to the present.
Quick answer
The Present Perfect of the verb to know is have / has known.
Example: I have known him for 10 years.
Full conjugation in the Present Perfect
| Pronoun | Form | Contraction |
|---|---|---|
| I | have known | I've known |
| You | have known | You've known |
| He / She / It | has known | He's / She's / It's known |
| We | have known | We've known |
| You (pl.) | have known | You've known |
| They | have known | They've known |
Common mistakes to avoid
1. I know him for 10 years ❌
This is a very common mistake. When you have known someone since a time in the past and you still know them, use the Present Perfect, not the Present Simple. Say I have known him for 10 years, never I know him for 10 years.
2. I have knew ❌
After have / has, use known (the past participle), not knew (the Past Simple). Say I have known her for years, never I have knew her.
3. I have known him since 10 years ❌
With have known, use for + a length of time (for 10 years) or since + a starting point (since 2014). For answers “how long?”. Since answers “from when?”.
Practice quiz
Going further
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Frequently asked questions
What is the present perfect of know?+
It is have known or has known. Known is the past participle of know. It is very common for a friendship or a fact that started in the past and is still true: I have known him for years.
How do you say I have known him for 10 years?+
Say I have known him for 10 years. When you have known someone since a time in the past and you still know them now, English uses the Present Perfect. I know him for 10 years is a very common mistake.
What is the difference between I know and I have known?+
I know him is about now, with no length of time. I have known him for 10 years joins the past and the present: it says how long. When you add for or since, use the Present Perfect.
Is it knew or known?+
Knew is the Past Simple, for a finished time: I knew her in 2010 (we are not in contact now). Known is the past participle, used in the Present Perfect: I have known her since 2010 (I still know her).
How do you make negatives and questions with have known?+
Negative: I haven't known him for long, She hasn't known them for long. Question: put have or has before the subject: Have you known him for long? How long has she known her best friend? Known does not change.
Related pages: know Present Perfect
Pages on a similar topic or with a similar use, so you can keep exploring.
Updated on 12 November 2026 by the Big Challenge teaching team. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999. Our teaching approach →
The Big Challenge · Updated on 12 November 2026 · Source: www.thebigchallenge.com/bl/academy/learn-english/verbs/know/present-perfect
© The Big Challenge. Copying allowed for classroom use. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999.
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More forms of the verb to know are coming soon.