cheatsheet
Time & dates
Time and dates in Japanese run on a simple frame — number + counter — but two spots will trip you up: minutes (the "fun/pun" sound flips depending on the number) and the first ten days of the month (almost all irregular, leftovers from old native readings). Memorize those two patches and the rest is just plugging numbers in. Everything below is in polite, tourist-safe register.
Hours (ji)
Hour = number + 時 (ji). Only 4, 7, 9 are irregular: yo-ji (not yon-ji), shichi-ji, ku-ji. Add 午前 (gozen, AM) / 午後 (gogo, PM) before the hour. Japan uses 12-hour clock in speech, 24-hour on signs/timetables.
Minutes (fun / pun) + half
THE HARD PART. The counter is 分, read fun OR pun depending on the number before it. Rule of thumb: 1, 3, 4, 6, 8, 10 → -pun; 2, 5, 7, 9 → -fun. The number itself also shifts (ip-pun, sanp-pun, yonp-pun, rop-pun, hap-pun, jup-pun). 半 (han) = half past.
Asking & telling time
何時 (nan-ji) = 'what time'. To say a full time, stack hour + minute: gogo san-ji juugo-fun = 3:15 PM. Add 〜から (kara, from) / 〜まで (made, until) for ranges — handy for opening hours.
Days of the week
Each day = element + 曜日 (youbi). The elements map to a planet/element: moon, fire, water, wood, metal/gold, earth, sun. 何曜日 (nan-youbi) = 'what day of the week'. On signs you'll often see just the first kanji: 月, 火, 水, etc.
Relative days (today / tomorrow / yesterday / morning / tonight)
These are everyday words — learn them cold. 今日 (kyou), 明日 (ashita), 昨日 (kinou) are the three workhorses. Note 明日 is officially 'ashita' in casual speech (also asu/myounichi more formally).
Months & dates
MONTHS are easy: number + 月 (gatsu), e.g. ichi-gatsu = January. Watch 4月 shi-gatsu, 7月 shichi-gatsu, 9月 ku-gatsu (irregular like the hours). DATES are the hard patch: day-of-month = number + 日 (nichi), BUT the 1st–10th plus the 20th use old native readings you must memorize. 11th onward is mostly regular (number + nichi), with 14/20/24 as exceptions.
Useful time words
Glue words for talking about schedules, trains, and 'how long'. 〜分かかります (~fun kakarimasu, 'it takes ~ minutes') is gold for transit. 時間 (jikan) = both 'time' and the counter for 'hours' (duration), distinct from 時 (ji, clock o'clock).