Today we’re going to discuss the Japanese counting system. Specifically, we’ll be looking at Japanese count words or counters. Counting in Japanese can be confusing for non-native speakers because virtually anyone or anything that you can count must be followed by the appropriate counter. These counters typically (but not always) reflect some quality of what you are counting: the shape of an object, the size of an animal, the unit of time being expressed, etc.
Pretty much everything that you can think of has an appropriate counter. For the handful of things that don’t you’ll need to use the older native Japanese counting system (hitotsu, futatsu, mittsu, etc.) instead of the more common Sino-Japanese counting system (ichi, ni, san, etc.) Also keep in mind that when combining a number with a counter, the pronunciation of the number and/or counter might change. Make sure that you know about these exceptions before you begin using any of the following counters.
本 (hon): long, cylindrical objects
枚 (mai): flat, thin objects
個 (ko): small and compact objects
杯 (hai): liquid in cups, glasses, bowls, etc.
冊 (satsu): bound objects (i.e. books and magazines)
台 (dai): vehicles and other large machinery
階 (kai): floor
件 (ken): houses and other buildings
足 (soku): pairs of shoes, socks, and other types of footwear
通 (tsuu): letters (of the paper variety, not of the alphabet)
匹 (hiki): Small animals (dogs and cats), insects, and fish
頭 (tou): large animals (bears, elephants, horses, etc.)
羽 (wa): birds
人 (nin): informal counter for people. Note that one person (hitori) and two people (futari) are exceptions.
名( mei): formal counter for people.
回 (kai) and 度 (do): number of times (once, twice, three times, etc.)
番 (ban): ordinal numbers (first place, second place, number one, number two, etc.)
等 (tou): class or grade
時間 (jikan): hours
分 (fun): minutes
秒 (byou): seconds
週間 (shuukan): weeks
か月 (kagetsu): months
年間 (nenkan): years
歳/才 (sai): age of a person (in years)