Translation guide
The English word "inside" can refer to physical interior spaces, internal states, time limits, and more. This guide helps you choose the right Japanese expression for each meaning.
Expressing that something is located within a physical space, building, room, or container.
The most common and versatile word for 'inside'. Used for physical interiors of spaces, containers, and objects.
箱の中に猫がいます。
There is a cat inside the box.
It's warm inside the room.
More formal and often used for the interior of buildings, organizations, or systems. Can sound technical.
Photography is prohibited inside the building.
Emphasizes the inner side or surface of something, often contrasted with 'outside' (外側).
The door is locked from the inside.
Expressing that something happens or is completed within a certain period or limit.
Used after a time expression to mean 'within' that period. Often used with deadlines.
I'll be back inside an hour.
Please submit the report inside this week.
Means 'while still within' a period. Implies doing something before the period ends.
Let's go home while it's still light (inside the daylight hours).
Referring to one's inner mental or emotional state, not visible externally.
Referring to privileged information or being a member of an organization.
Describing something turned so the inner surface becomes the outer surface.
Referring to the interior of a living body, such as organs or stomach.
While 中 (なか) is the most common translation, it is not always natural. For time limits, use 以内. For internal feelings, 心の中 is better. For inside out, use 裏返し.
中 (なか) is the general word for physical inside. 内 (うち) often means 'within' a group, home, or abstract boundary. 内部 (ないぶ) is formal and used for organizations or structures.
内心ではほっとした。
Inside, I felt relieved.
Insider trading is illegal.
To turn something inside out or upside down. More forceful.
Please turn your pockets inside out and show me.