どれ/どの/どちら

In Japanese, choosing the correct word for 'which' depends on how many things you are choosing from, how the word fits into the sentence, and the level of politeness.

1. The Number of Options and Animacy

• どちら： Primarily used when choosing between exactly two items. It can refer to things, people, or places (meaning 'which of the two'—see Section 5 for its use as a polite 'where'). However, it is also frequently used as a polite version of どれ for three or more items, and its casual form どっち is also commonly used for three or more items in everyday speech (though this is technically incorrect and should be avoided on formal tests like the JLPT).
• どれ / どの： Used when choosing from three or more items. Importantly, どれ should generally be used for non-humans (things and animals); using it to refer to people is considered impolite and should be avoided. For three or more people, use 誰 (who) instead. However, the determiner どの can safely be used for people when attached to a noun (e.g., どの人、どの先生).

2. Grammatical Function

• Pronouns (Stand Alone):
  どれ and どちら are pronouns. They stand alone and are usually followed by particles like が or を. They mean 'which one'.
• Determiners (Before Nouns):
  To say 'which [noun]', you must use a determiner. For three or more items, use どの. For two items, use どちらの (or its casual equivalent, どっちの). These must be followed immediately by a noun (e.g., どの本、どちらのペン). Note: While どちらの is standard for two items, native speakers sometimes use どの for two items in casual speech. To say 'which [noun]' for three or more items, always use どの, not どれの. どれの is only used to mean 'which one's' (e.g., これはどれのフタですか - Which one's lid is this?).

3. Making Comparisons

• Two Items: When asking someone to choose between two specific things, use the pattern A と B（と）、どちらが [adjective] ですか (Between A and B, which is [adjective]?). To answer, use the pattern 〜のほうが (e.g., Aのほうが好きです - I prefer A).
• Three or More Items: When comparing three or more items, use the pattern [Category] で、どれが一番 [adjective] ですか (Among [Category], which is the most [adjective]?). Note that どれ is only used when the category consists of non-humans (things and animals). For people, you must use だれ (e.g., 家族でだれが一番...); for places, どこ; and for time, いつ. To answer, use the pattern 〜が一番 [adjective] です (e.g., Aが一番好きです - I like A the most).

4. Answering 'Both', 'All', or 'Neither'
When you don't want to choose just one, you can use these common expressions:

• For Two Items: どちらも (both), どちらでも (either is fine), どちらも〜ない (neither).
• For Three or More Items: どれも (all of them), どれでも (any of them is fine), どれも〜ない (none of them).

5. Other Meanings of どちら
Besides meaning 'which', どちら is also the standard polite word for 'where' (polite for どこ). For example, どちらから来ましたか means 'Where are you from?'. Furthermore, どちら is a standard polite alternative for 'who' (polite for 誰), even when not choosing between options. It is often used with 様（さま）as どちら様 to politely ask for someone's identity (like 'Who is calling?' on the phone).

6. The Ko-So-A-Do Connection
A great way to become confident with these words is to remember their matching answers in the 'Ko-So-A-Do' system:

• Question: どれですか？ → Answer: これです (This one)
• Question: どの本ですか？ → Answer: この本です (This book)
• Question: どちらですか？ → Answer: こちらです (This one / This way)