階 (kai/gai): Counting Floors
Quick Answer: 階 counts building floors: 一階 (いっかい, 1st floor), 二階 (にかい, 2nd), 三階 (さんがい, 3rd). Important: Japanese ground floor = 一階 (1F), same as American English.
Navigating buildings floor by floor
Category: Counters
The Rule
階 counts building floors: 一階 (いっかい, 1st floor), 二階 (にかい, 2nd), 三階 (さんがい, 3rd). Important: Japanese ground floor = 一階 (1F), same as American English. Sound changes: 1 = いっかい, 3 = さんがい, 6 = ろっかい, 8 = はっかい, 10 = じゅっかい. Basement: 地下一階 (ちかいっかい, B1).
Why This Matters
Unlike British English (where ground floor = 0 and first floor = 1), Japanese counting matches American English: the ground level is 一階 (1st floor). The main pitfall is the sound change on 三階 (さんがい, not さんかい) — this is one of the most commonly tested points in Japanese language exams.
Examples
• エレベーターで五階に行ってください。 — "Please take the elevator to the 5th floor." [ごかい = 5th floor] • 三階にレストランがあります。 — "There's a restaurant on the 3rd floor." [さんがい = 3rd floor (sound change!)] • このビルは何階建てですか？ — "How many floors does this building have?" [何階 = なんがい / なんかい. 階建て = number of stories] • 地下二階に駐車場があります。 — "There's a parking lot on basement level 2." [地下にかい = B2 — 地下 prefix for basements]
Common Mistakes
❌ さんかい ✅ さんがい → 3rd floor is さんがい (voiced), not さんかい. This is one of the most common counter mistakes and a classic exam question ❌ 一番下の階 ✅ 一階 / 地下一階 → Be specific: 一階 = ground/1st floor, 地下一階 = first basement. Don't use vague descriptions when floor numbers are expected
Quick Tip
The tricky readings: 一階 (いっかい), 三階 (さんがい), 六階 (ろっかい), 八階 (はっかい/はちかい), 何階 (なんがい). The rest are regular: にかい, よんかい, ごかい, ななかい, きゅうかい.
The tricky readings: 一階 (いっかい), 三階 (さんがい), 六階 (ろっかい), 八階 (はっかい/はちかい), 何階 (なんがい). The rest are regular: にかい, よんかい, ごかい, ななかい, きゅうかい.
Examples
Common Mistakes
Incorrect: さんかい → Correct: さんがい. 3rd floor is さんがい (voiced), not さんかい. This is one of the most common counter mistakes and a classic exam question
Incorrect: 一番下の階 → Correct: 一階 / 地下一階. Be specific: 一階 = ground/1st floor, 地下一階 = first basement. Don't use vague descriptions when floor numbers are expected
Quiz
How do you read 三階 (3rd floor)?