Knew vs Understood

When to use each in English, with meaning, register, and examples.

Knew

Top 1,000 (very common)

Understood

Top 1,000 (very common)

	Knew	Understood
Pronunciation	🇬🇧 //njuː// 🇺🇸 //nuː//	🇬🇧 //ˌʌndəˈstʊd// 🇺🇸 //ˌʌndərˈstʊd//
Meaning	understood or was aware of something in the past	To know or comprehend something.
Example	She knew the answer to the question.	After the explanation, I finally understood the problem.
Register	Neutral	Neutral
How common	Top 1,000 (very common)	Top 1,000 (very common)
Collocations	knew the truth, knew the risks, knew the answer, knew each other, never knew	fully understood, clearly understood, never understood, easily understood
Antonyms	forgot, ignored	misunderstood, confused, ignorant
Common mistakes	Confused with 'know' (present tense) vs 'knew' (past tense), 'Knew' is sometimes incorrectly used in continuous forms (e.g., 'was knew')	Confused with 'understand' in different tenses., Using 'understood' in present tense situations., Mispronouncing the word, leading to misunderstandings.
Usage notes	Used to express past knowledge or understanding. Appropriate in most contexts, but avoid in overly formal writing.	Use 'understood' in past tense contexts or when confirming comprehension. Avoid in formal writing where 'comprehended' may be preferred.

See it in real clips

And she knew a zillion old jokes.

Sherlock › S1 E1

if you knew - you're the one who chooses.

Now, Bubba had told me everything he knew about shrimping,

And she knew a zillion old jokes.

Sherlock › S1 E1

if you knew - you're the one who chooses.

Knew

House Of Dragons › S1 E1

Understood, your grace.

Breaking Bad › S1 E1

You understood what I've just said to you?

Breaking Bad › S1 E2

Understood?

House Of Dragons › S1 E1

Understood, your grace.

Breaking Bad › S1 E1

You understood what I've just said to you?

Understood

Frequently asked questions: Knew vs Understood

What's the difference between Knew and Understood?

Knew: understood or was aware of something in the past Understood: To know or comprehend something.

Can you show an example of each?

Knew: She knew the answer to the question. Understood: After the explanation, I finally understood the problem.

Can I use Knew and Understood interchangeably?

Not always. Knew and Understood are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.