"to know something by heart"

Meaning: to have learned or memorized something completely and perfectly

Similar Expressions

• I know this song by heart.
• I know this whole song perfectly.
• I have memorized this song completely.

When do we use it?

We use this phrase when we want to emphasize that we know something perfectly and completely. This phrase does not add any new information, it just emphasizes how well we know something.

• I know this poem.
• I know this poem well.
• I know this poem by heart.

How do we use it?

We always follow this sentence pattern when using this phrase.

Subject + know + something + by heart…

• I know this neighborhood by heart.
• She knows all the singer's songs by heart.
• He knows every line of this movie by heart.

We can make similar sentences using the verbs "learn" and "memorize" instead of "know".

• I memorized this poem by heart.
• She learned all the lyrics of the song by heart.

Example English Conversations

A) Do you know this song?
B) Are you kidding me? This is my favorite song. I know it by heart.

Adding expressions and idioms to your vocabulary will help you become a better English speaker. You do not need to learn a million expressions or idioms at one time! If you study new English expressions and idioms steadily and consistently, then your vocabulary will get better and better. Use these free English lessons to expand your vocabulary and learn useful English idioms, slang, and expressions.