Translation guide
Expresses that multiple things happen simultaneously or that something happens suddenly and completely.
Multiple actions or events occurring at the same time.
The most common and versatile way to say 'all at once' when multiple things happen together. Can be used for actions, events, or objects.
He is good at doing two things at once.
Please don't eat everything all at once.
Emphasizes exact simultaneity. Often used in more formal or technical contexts.
The two incidents happened all at once.
Used when a group of people or things act together at the same moment, often in a coordinated way.
The students stood up all at once.
Something happening abruptly, without warning.
The standard word for 'suddenly'. It can be used for events that occur all at once, catching you off guard.
All at once, it started raining.
More colloquial than 突然, often implies something happening without any prior notice or buildup.
Similar to 突然 but can also imply a rapid change. Common in everyday speech.
Doing something in a single action, without stopping or dividing it.
Implies doing something in one burst, without pausing. Often used for drinking, reading, or completing tasks.
He drank the beer all at once.
Means doing things collectively or in a batch. Useful when you group tasks or items.
I'll answer the questions all at once.
一度に focuses on multiple things happening at the same time, while 一気に emphasizes doing something in one continuous, uninterrupted action. For example, 一度に二つのことをする (do two things at once) vs 一気に走る (run without stopping).
Avoid directly translating 'all at once' as 全部一度に in every context. It can sound unnatural. Use the appropriate phrase based on whether you mean simultaneously, suddenly, or in one go.
いきなり彼が部屋に入ってきた。
He came into the room all at once.
Everything changed all at once.
I read the book all at once.