Mastering the Japanese Counter ~台 (dai): Machines, Vehicles, and Appliances

In Japanese, you cannot just say 'one car' or 'two computers' using just the number. You need a counter. The structure is usually [Noun] + [Particle] + [Number] + [Counter]. For example, if you want to say 'two cars,' you would say kuruma ga nidai. It feels a bit like saying 'two units of cars' in English. You can also place the number and counter before the noun with the particle no, like nidai no kuruma, but the first way is much more common in daily conversation. Unlike some other counters that change their sounds (like ichiyuu becoming ippon), ~台 stays exactly the same no matter what number comes before it. This makes it a great 'confidence booster' grammar point. Even native speakers appreciate when you use the correct counter, as it makes your Japanese sound much more natural and polished.

1. 1Forming ~台 is as easy as counting to ten. You just take the standard Chinese-style numbers (ichi, ni, san...) and add dai to the end. There are no irregular readings here, which is basically a grammar miracle!
2. 2ichidai (one machine)
3. 3nidai (two machines)
4. 4sandai (three machines)
5. 5yondai (four machines) - Note: Use yon, not shi.
6. 6godai (five machines)
7. 7rokudai (six machines)
8. 8nanadai (seven machines) - Note: nanadai is more common than shichidai.
9. 9hachidai (eight machines)
10. 10kyuudai (nine machines) - Note: Use kyuu, not ku.
11. 11juudai (ten machines)

You will use ~台 for a huge variety of items. If it has a motor, a screen, or complex internal parts, it probably takes ~台.

• Vehicles: Cars (kuruma), bicycles (jitensha), motorcycles (baiku), and even buses or trucks. If it has wheels and moves people, use ~台.
• Electronics: Computers (pasokon), televisions (terebi), cameras (kamera), and printers.
• Household Appliances: Washing machines (sentakuki), refrigerators (reizouko), and microwave ovens (renji).
• Large Musical Instruments: This is a fun one! Pianos (piano) and organs use ~台 because they are seen as large, complex mechanical structures.
• Furniture (Sometimes): Large items like beds (beddo) often use ~台, though some people use ~つ for smaller furniture. When in doubt with a big bed, ~台 is a safe bet.

Imagine you are at a car rental desk. You might say, kuruma o nidai kashite kudasai (Please rent me two cars). Or if you are at an electronics store, you might ask, kono pasokon wa ichidai ikura desu ka? (How much is one of these computers?). It is a very practical counter for shopping and logistics.

Even though ~台 covers a lot, it is not for everything.

• Small Handheld Items: While computers use ~台, small items like smartphones (sumaho) can be tricky. Many people use ~台 for smartphones because they are 'machines,' but for very small gadgets like a USB stick or a simple calculator, people often revert to the general counter ~つ or ~個 (ko).
• Non-Mechanical Items: Do not use it for books, clothes, or food.
• Living Things: Never use ~台 for people or animals. That would be like calling your cat a toaster, which might offend the cat.
• Boats and Planes: While these are vehicles, they often have their own special counters (~seki for ships and ~ki for planes). However, in casual speech, you might hear ~台 for small drones or toy planes.

The biggest mistake is over-relying on the general counter ~つ. While ~つ is a great safety net, using ~つ for a car sounds a bit childish. It is like a traffic light; if you use the wrong color, things get confusing! Another mistake is trying to apply the 'small item' rule to things like cameras. Even a tiny digital camera is a complex machine, so stick with ~台. Also, watch your pronunciation of 'four.' Stick to yondai. Saying shidai sounds very strange and might be confused with other words. Finally, remember that ~台 is for the *unit* itself. If you are counting the *wheels* on the car, that is a different counter entirely!

You might get ~台 confused with ~個 (ko) or ~枚 (mai).

• ~台 vs ~個: ~個 is for small, round, or compact objects (like an apple or a small box). ~台 is for functional machines. A microwave is ~台, but the bowl inside it is ~個.
• ~台 vs ~枚: ~枚 is for flat, thin objects. A TV is ~台 because it is a machine, but the screen protector you put on it is ~枚 because it is a flat sheet.
• ~台 vs ~機 (ki): ~機 is used for large aircraft or industrial machinery. For your home printer, use ~台. For a Boeing 747, use ~機.