階かい

か

い

Common wordJLPTN3Freq.FrequencyTop 1,000

Meanings

floor; storey

Refers to a level or storey of a building. Often used as a suffix after a number or descriptor, e.g. 二階 (second floor).

Rare standalone noun for stairs; the reading きざはし is more common for this meaning. Modern Japanese usually uses 階段 (かいだん).

〈数かず〉階かい建だてa building of ~ floors
このマンションは十じゅっ階かい建だてです。
This apartment building has ten floors.
〈数かず〉階かいに上あがるto go up to the ~th floor
エレベーターで五ご階かいに上あがった。
I went up to the fifth floor by elevator.
〈場ば所しょ〉の〈数かず〉階かいにあるto be located on the ~th floor of a place
本ほん屋やはデパートの三さん階かいにあります。
The bookstore is on the third floor of the department store.
何なん階かいですかwhat floor is it?
すみません、トイレは何なん階かいですか。
Excuse me, what floor is the restroom on?

階かい段だんN5sense 2
階段 is the everyday word for a staircase, while 階 (かい) is a rare, literary term for stairs that has largely been replaced by 階段 in modern Japanese.
フロア
階 is the native Japanese word/counter for a building's storey, while フロア is a borrowed word often used in business or casual contexts for the same idea.

階かい層そうN1sense 1
階層 means a social class or hierarchical layer, while 階 refers to a physical floor of a building, even though both words share the kanji 階.
階きざはし sense 2
Written identically as 階, きざはし is a classical, literary reading meaning stairs, while かい is the everyday reading meaning a building floor or the counter for floors.
層そうN1
階 is the everyday counter for a building's floors (三階 = third floor), while 層 as a counter is a more formal or technical term often used in architectural or structural descriptions.

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界かいN2
界 and 階 are both pronounced かい, but 界 means a sphere or world (as in 政界) while 階 is the counter for floors or stories of a building.
回かいN4
階 (floor/story of a building) sounds identical to 回 but counts building levels rather than occurrences.

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The kanji 階 originally depicted steps or a staircase. The reading かい is the Sino-Japanese on'yomi. The word is used broadly for floors and levels.