Translation guide
The English phrase 'be ready' covers a range of states from immediate preparedness to general willingness. In Japanese, the best expression depends on whether you mean physically prepared, mentally resolved, or having finished preparations.
The speaker is ready to go, start, or respond right now.
Standard way to say you are ready, emphasizing that preparations are complete.
I'm ready now.
Are you ready to leave?
Similar to 準備, but often implies things are laid out or arranged for a specific purpose.
The documents are ready.
Casual way to say 'I'm ready whenever' or 'anytime is fine'.
I'm ready whenever. Let's go.
The speaker is mentally prepared or enthusiastic about doing something.
Implies mental readiness, often for something difficult or challenging.
He is ready to accept the consequences.
Means 'ready and willing' in a positive sense, often used in offers.
I'm ready to help. (lit. I'll gladly help.)
Very casual, means 'full of motivation' or 'raring to go'.
I'm ready to go today!
The speaker has completed preparations for an event or task.
The speaker is prepared to go out or start a journey.
Specifically for being ready to go out.
Are you ready to go out yet?
Casual way to ask if someone is ready to go.
Ready to go? We'll be late.
準備 (junbi) focuses on the process of preparing, while 用意 (yōi) emphasizes the state of having things ready for use. In many cases they are interchangeable, but 用意 is more about tangible arrangements.
Prepare for a trip (process).
The documents are ready (arranged).
English uses 'ready' in many idiomatic ways (e.g., 'ready money', 'ready wit') that do not translate directly. Stick to the core meanings of preparedness and willingness.
The report will be ready by tomorrow.
Formal/work context.