開ける describes opening something; 開く（あく） describes something opening.

The idea

With 開ける, the object normally takes を: 窓を開けます. With 開く, the thing that opens takes が: 窓が開きます. 窓が開いています describes the resulting open state. The polite past forms are 開けました and 開きました.

Patterns to compare
FormExample
開あける窓まどを開あけます
開あく窓まどが開あきます
開あいている窓まどが開あいています

Examples

  • 私わたしは窓まどを開あけます。I open the window.
  • ドアがゆっくり開あきます。The door opens slowly.
  • 店みせは九時くじに開あきます。The shop opens at nine.
  • 箱はこを開あけてください。Please open the box.
  • 風かぜで窓まどが開あきました。The window opened because of the wind.
  • 窓まどが開あいていますね。The window is open, isn’t it?

Read-aloud uses a synthetic Japanese voice available on your device. Voice quality and availability vary; it does not assess your pronunciation.

Watch out

An intransitive sentence does not rule out a cause: 風で窓が開きました says the wind opened it. 開く also has the different reading ひらく in other uses; this lesson focuses on あく.

Try it yourself

  1. Choose the correct form: I open the window. 私わたしは窓まどを＿＿。（開あけます／開あきます）

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    開けます

    The speaker acts on the window, marked by を, so use 開けます.

  2. Choose the correct form: The door opens slowly. ドアがゆっくり＿＿。（開あけます／開あきます）

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    開きます

    The door is what opens, marked by が, so use 開きます.

  3. Choose the correct form: Please open the box. 箱はこを＿＿ください。（開あけて／開あいて）

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    開けて

    The box is the object of the request; the て-form of 開ける is 開けて.

Use it today

Describe opening a door, the door opening and the door being open.