Mastering です and だ: The Japanese Copula

です and だ are the Japanese equivalents of “is/am/are”. Choosing between them sets the tone of your speech.

です — the polite form

Use です in most everyday and formal situations: 学生です (I am a student). Its past form is でした, and its negative is ではありません / じゃないです.

だ — the casual form

だ is used in casual speech and writing: 学生だ. Among friends, だ is often dropped entirely. Its negative is じゃない and past is だった.

When to use which

• です — with teachers, strangers, customers, and in the workplace.
• だ / plain form — with close friends and family.

A beginner tip

When in doubt, use です. It is always safe and polite. As you gain exposure, you will learn when casual speech is appropriate.