How to Use the Past Tense of Japanese Adjectives | かったです・でした Explained

Introduction

Want to say things like:

• “It was cold yesterday.”
• “The movie was interesting.”
• “The hotel wasn’t quiet.”

In Japanese, both い-adjectives and な-adjectives have special conjugation patterns for the past tense. In this article, you’ll learn how to turn “is fun” into “was fun” and how to say something was not nice, new, or energetic.

Let’s learn how to talk about the past using adjectives!

1. What Are Japanese Adjective Types?

There are two types of adjectives in Japanese:

• い-adjectives (e.g. たのしい, さむい)
• な-adjectives (e.g. しずか, げんき)

Each type has a different rule when you change them into the past tense.

2. How to Conjugate い-Adjectives into Past Tense

Affirmative (was ___)

Rule: Drop い and add かったです.

Negative (was not ___)

Rule: Drop い and add くなかったです (casual)
→ or use くありませんでした (formal)

Special Case: いい → よかった

The adjective いい（good） becomes:

• Positive: よかったです
• Negative: よくなかったです

Not: いかったです or いくなかったです

3. How to Conjugate な-Adjectives into Past Tense

Affirmative (was ___)

Rule: Drop な and add でした

Negative (was not ___)

Rule: Drop な and add じゃなかったです (casual)
→ or use ではありませんでした (formal)

4. Practice: Affirmative and Negative Forms

な-Adjectives

い-Adjectives

5. Real-Life Examples

6. FAQ – Frequently Asked Questions

Conclusion

Now you know how to talk about the past with confidence in Japanese!

✅ Conjugate い-adjectives: たのしい → たのしかったです
✅ Conjugate な-adjectives: げんき（な）→ げんきでした
✅ Use both casual and formal negative forms

🎯 Try writing 3 past-tense sentences about your weekend!