Quick answer: “By Heart” means to know something perfectly from memory, without needing notes.
By heart — to have memorised something so thoroughly that you can recall it entirely from memory without needing to look at any notes, prompts, or written text.
Origin & History
This phrase has ancient roots stretching back to classical antiquity. In Greek, Latin, and early European thought, the heart — not the brain — was considered the seat of memory, emotion, and understanding. To know something "by heart" therefore meant to have it stored in the very core of your being. The expression appears in English from at least the 14th century and is found in the works of Chaucer.
Despite advances in neuroscience, the idiom remains firmly embedded in everyday English as the natural way to describe perfect memorisation. It is used by teachers, performers, musicians, and language learners the world over. Idioms like this are the kind of expression documented in general reference works such as the Cambridge Dictionary, which record how figurative meanings develop in everyday English.
Example Sentences
| Sentence | Context |
|---|---|
| After weeks of rehearsal, the children knew all their lines by heart. | School play |
| She learnt the periodic table by heart before her chemistry exam. | Academic study |
| He can recite every verse of the poem by heart — it's impressive. | Literature |
| The pianist had the entire concerto by heart and performed without sheet music. | Music performance |
| I've driven this route so many times I know every turn by heart. | Everyday familiarity |
| New recruits are expected to learn the safety procedures by heart. | Workplace training |
Use It in Conversation
Dialogue Example
Teacher: Maria, can you recite the first stanza of the poem for us?
Maria: Yes, I've learnt it by heart. "I wandered lonely as a cloud / That floats on high o'er vales and hills..."
Teacher: Excellent. That took real dedication. Well done.
How to Use It
The most common collocations are "know by heart", "learn by heart", and "recite by heart". It always follows the object: "I know it by heart" not "I know by heart it". The phrase is fixed — do not alter the preposition. In British English, "off by heart" is an equally acceptable and widely used variant.
Common Mistakes
Mistakes to Avoid
I memorised the poem by heart.
I learnt the poem by heart (or: I memorised the poem). — "Memorise by heart" is redundant; use "learn by heart" or just "memorise".
She knows it in heart.
She knows it by heart. — The correct preposition is always "by", not "in".
Similar Idioms
Practise This Idiom
Want to understand the grammar behind this? Explore our Grammar guides.
Quick Check: By Heart
2 questions — test what you just learned.
1. What does “By Heart” mean?
2. Complete the sentence: “After weeks of rehearsal, the children knew all their lines _____.”
Frequently Asked Questions
What does "by heart" mean?
"By heart" means to have memorised something so thoroughly that you can recall it entirely from memory, without needing to look at any notes or prompts.
Where does "by heart" come from?
The phrase has ancient roots. In classical and medieval times, the heart was believed to be the seat of memory and intelligence, not the brain. To know something 'by heart' therefore meant to have it stored in the deepest part of yourself. The expression appears in English from the 14th century.
Can you give an example of "by heart" in a sentence?
Example: "After weeks of rehearsal, the children knew all their lines by heart." It means they could recite them from memory without reading from the script.
What verbs are used with "by heart"?
The most common verbs are 'know by heart' and 'learn by heart'. You can also say 'recite by heart', 'memorise something so you know it by heart', or 'have something by heart'.
What CEFR level is "by heart"?
This idiom is introduced at A2–B1 level. It is one of the most fundamental and widely recognised English idioms and is used across all age groups.
What are common mistakes with "by heart"?
A common error is saying 'in heart' instead of 'by heart'. The correct fixed preposition is 'by'. Also avoid 'memorise by heart' — it is redundant; say 'learn by heart' or simply 'memorise'.
What is the difference between "know by heart" and "learn by heart"?
'Know by heart' describes the current state — you already have it in memory. 'Learn by heart' describes the process of committing something to memory. Both are correct and commonly used.
What idioms are similar to "by heart"?
Related expressions include 'off by heart' (British variant meaning the same thing), 'off the top of your head' (recalling without preparation), and 'commit to memory' (the formal equivalent).
How do I practise idioms like "by heart"?
Use LexFizz's Flash Cards and Flip Tiles. Ironically, learning idioms 'by heart' is a great way to practise the idiom itself — try memorising the definition and an example sentence.
Is "by heart" used the same way in British and American English?
Yes, 'by heart' is used identically in both. British English also uses 'off by heart' as an equally common variant, but American English rarely uses the 'off' version.