～かは～によって違う【かは～によってちがう】

The structure ～かは～によって違う expresses that something differs or changes depending on a certain factor. It translates to "whether/what/how ~ depends on ~" or "~ differs depending on ~."

The first part uses an embedded question (using question words like なん何, どう, いくら, どのくらい, or the yes/no question marker か) to indicate the thing that varies, while the second part introduced by によって indicates the factor that causes the variation.

Basic pattern

The embedded question can use any interrogative word:

• 何か (what):
  なん何がひつよう必要かはじょうきょう状況によってちがう違う。

  What is needed differs depending on the situation.
• どうか (whether):
  さんか参加するかどうかはよてい予定によってちがう違う。

  Whether I participate depends on my schedule.
• どのくらい (how much/long):
  どのくらいじかんがかかる時間がかかるかはひと人によってちがう違う。

  How long it takes differs depending on the person.

Variations

Instead of ちがう違う, you may also see ことなる異なる (a more formal synonym) or かわる変わる (to change). The meaning remains the same.

The topic marker は after か is important – it marks the embedded question as the topic and sets up the "depends on" structure. Dropping it changes the nuance and can sound unnatural in this pattern.