If you had to pick the single most useful counter for modern life, 台（だい） would be a strong candidate. It counts cars, computers, phones, televisions, refrigerators, washing machines, cameras, printers, bicycles, air conditioners — essentially the machines and vehicles that fill a household and a city. And it comes with a rare gift: 台 has no sound changes at all. Every number attaches cleanly, so once you learn the semantic field, there is nothing left to trip over.
The core idea: things with a base or platform
The kanji 台 means stand, pedestal, base, platform (as a standalone noun, 台 is a "stand" — a 台 you set things on). That original sense is the key to its counter use: 台 counts equipment that sits on or is built around a base or chassis. A car has a chassis; a washing machine has a housing; a TV has a stand; a computer has a case. All of them "have a body you'd mount on a platform," and all of them take 台.
This is a wide, forgiving semantic field. If a thing is a piece of machinery, a vehicle, or an electrical appliance, your first guess should be 台 — and you will be right the overwhelming majority of the time.
駐車場に車が三台停まっている。
chūshajō ni kuruma ga san-dai tomatte iru
Three cars are parked in the lot.
在宅勤務用にパソコンを二台使っている。
zaitaku kinmu-yō ni pasokon o ni-dai tsukatte iru
I use two computers for working from home.
この店にはコピー機が一台しかない。
kono mise ni wa kopī-ki ga ichi-dai shika nai
This shop has only one copier.
The readings — all regular
Here is why 台 is a relief after 羽 and 本: because だい begins with a voiced consonant (d), neither of the two euphonic forces can touch it. Gemination needs a k/s/t/h/p to double, and voicing needs a voiceless consonant to soften — だい offers neither. So the readings are boringly, wonderfully predictable.
| Number | Reading |
|---|---|
| 一台 | いちだい (ichi-dai) |
| 二台 | にだい (ni-dai) |
| 三台 | さんだい (san-dai) |
| 四台 | よんだい (yon-dai) |
| 五台 | ごだい (go-dai) |
| 六台 | ろくだい (roku-dai) |
| 七台 | ななだい (nana-dai) |
| 八台 | はちだい (hachi-dai) |
| 九台 | きゅうだい (kyū-dai) |
| 十台 | じゅうだい (jū-dai) |
| 何台 | なんだい (nan-dai) |
うちには自転車が四台ある。
uchi ni wa jitensha ga yon-dai aru
Our household has four bicycles.
このコインランドリーには洗濯機が十台並んでいる。
kono koin-randorī ni wa sentakuki ga jū-dai narande iru
This laundromat has ten washing machines lined up.
The semantic range in practice
It helps to see just how much 台 swallows. All of the following are counted with 台:
| Category | Examples (counted with 台) |
|---|---|
| Land vehicles | 車 (car), トラック (truck), バス (bus), 自転車 (bicycle), バイク (motorbike) |
| Computing | パソコン (PC), ノートパソコン (laptop), タブレット (tablet), スマホ (smartphone) |
| Home appliances | テレビ (TV), 冷蔵庫 (fridge), 洗濯機 (washer), エアコン (AC), 電子レンジ (microwave) |
| Office / other | プリンター (printer), コピー機 (copier), カメラ (camera), ピアノ (piano), ロボット (robot) |
Two entries usually surprise learners. First, the bicycle — it is long and pole-ish, so the instinct is 本, but a bicycle is a vehicle and takes 台. Second, the smartphone and the piano — a phone feels too small and a piano too big to share a counter with a bus, yet both are "machines with a body," so both are 台.
スマホを二台持ち歩くのは、正直めんどくさい。
sumaho o ni-dai mochiaruku no wa, shōjiki mendokusai
Carrying two smartphones around is honestly a hassle.
この工場にはロボットが何台あるんですか。
kono kōjō ni wa robotto ga nan-dai aru n desu ka
How many robots does this factory have?
Where 台 stops: boats and planes
The boundary of "machines and vehicles" has two important exceptions, because Japanese carves out special counters for craft that travel by water or air:
- Boats and ships take 隻（せき）, not 台: 船が一隻 (fune ga isseki, "one ship").
- Airplanes take 機（き）, not 台: 飛行機が二機 (hikōki ga niki, "two airplanes"). The same 機 counts drones and, often, aircraft-like machines.
So the mental rule is: 台 = machines and land vehicles; 隻 = watercraft; 機 = aircraft. Everything with wheels or a plug is 台; only the things that float or fly break away. For deciding between 台 and its neighbors 個 (small objects) and 本 (long things), see the counter-choosing guide.
港には大きな船が三隻停泊していた。
minato ni wa ōkina fune ga san-seki teihaku shite ita
Three large ships were moored in the harbor.
Common mistakes
❌ 車を三個買った。
Incorrect — 個 is for small, roundish objects, not vehicles.
✅ 車を三台買った。
kuruma o san-dai katta
I bought three cars.
個 is the tempting all-purpose counter (see 〜個), but a car is a machine, so it must be 台. Using 個 for a car sounds as odd as saying "three units of car" in English.
❌ 自転車が二本ある。
Incorrect — a bicycle is a vehicle, not a 'long cylindrical thing.'
✅ 自転車が二台ある。
jitensha ga ni-dai aru
There are two bicycles.
The bicycle looks long and thin, which lures learners toward 本 (see 〜本). But category beats shape here: it's a vehicle, so it's 台.
❌ パソコンを二個持っている。
Incorrect — a computer is a machine; 個 doesn't fit.
✅ パソコンを二台持っている。
pasokon o ni-dai motte iru
I have two computers.
❌ 飛行機が二台飛んでいる。
Incorrect — aircraft take 機, not 台.
✅ 飛行機が二機飛んでいる。
hikōki ga niki tonde iru
Two airplanes are flying.
❌ 船を一台借りた。
Incorrect — watercraft take 隻, not 台.
✅ 船を一隻借りた。
fune o isseki karita
I rented one boat.
Key takeaways
- 台（だい） counts machines, appliances, and land vehicles — anything with a body, chassis, or platform.
- The readings are completely regular: no gemination, no voicing. 一台 ichi-dai, 十台 jū-dai, 何台 nan-dai.
- Watch the two "shape-trap" members: bicycles and smartphones are 台 despite looking long or tiny.
- The only vehicles that leave 台 are boats (隻) and aircraft (機).
Now practice Japanese
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Start learning Japanese→Related Topics
- 〜個: Small ObjectsN5 — The all-purpose Sino counter 個 for small, compact objects — apples, eggs, chocolates — including the geminate readings いっこ, ろっこ, はっこ, じゅっこ and how it partners with つ.
- 〜本: Long Cylindrical ThingsN5 — The counter 本 for long, thin, cylindrical things — pens, bottles, umbrellas, even phone calls and home runs — and its notorious three-way sound change いっぽん・さんぼん・ろっぽん.
- Which Counter Do I Use?N4 — A practical decision guide to picking a Japanese counter — the top ten by object type, plus the つ and 個 fallbacks that let you keep talking when you're unsure.