Rack your brain
/ræk jɔː breɪn/neutralUK · US
What does “Rack your brain” mean?
Rack your brain means to think very hard while trying to remember or solve something
You rack your brain when the answer will not come easily. It might be a forgotten name, a password or a solution to a stubborn problem.
The phrase stresses effort rather than success. You can rack your brains all evening and still fail to remember.
When do people say it?
Use it for a difficult search for an answer, a memory or an idea. American English often uses “brain”; British English often uses “brains.”
“I racked my brain trying to remember where I'd parked the car.”
Is it formal or informal?
Register: neutral. It is most at home in both everyday conversation and professional writing. Most common in UK and US.
Where does it come from?
“Rack” suggests strain or pressure. The phrase treats difficult thinking as hard work for the brain.
Origin confidence: Disputed; treat with caution
How do you say “Rack your brain” in other languages?
Last updated 2026-09-19