Complete Guide to Japanese Adjective Conjugation (i-adj & na-adj)
Japanese adjectives come in two types: i-adjectives (い形容詞) and na-adjectives (な形容詞). Understanding how to conjugate both types is essential for JLPT N5 and N4 — and for everyday conversation in Japan.
i-Adjectives (い形容詞) — How They Change
i-adjectives always end in い in their dictionary form. To conjugate them, you remove the final い and add the appropriate ending. For example, 大きい (ōkii) — big — becomes:
- Negative: 大きくない (not big)
- Past: 大きかった (was big)
- Past negative: 大きくなかった (was not big)
- Te-form: 大きくて (being big, and…)
- Adverb (ku-form): 大きく (largely, in a big way)
- Conditional (ba-form): 大きければ (if big)
One important exception: いい (ii) — good — uses the older form よ as its stem: よくない, よかった, よくて. Always memorise this separately.
na-Adjectives (な形容詞) — How They Change
na-adjectives behave more like nouns. They take な when directly modifying a noun (きれいな人 — a beautiful person), and use だ / です conjugations otherwise. For example, 静か (shizuka) — quiet:
- Plain present: 静かだ
- Negative: 静かじゃない / 静かではない
- Past: 静かだった
- Past negative: 静かじゃなかった
- Te-form: 静かで (being quiet, and…)
- Adverb (ni-form): 静かに (quietly)
Why This Matters for JLPT and Work in Japan
JLPT N5 tests basic adjective conjugation in listening and grammar sections. N4 adds more complex patterns including te-form chaining (大きくて重い — big and heavy) and conditional forms. In the Japanese workplace, adjectives appear constantly in written reports, email, and verbal feedback. A manager might say もっと丁寧にしてください (please be more polite/careful) — recognising 丁寧 (ていねい) as a na-adjective and understanding its に adverb form is essential.
Study Tips
Start with the 20 most common i-adjectives (大きい, 小さい, 高い, 安い, 新しい, 古い, 長い, 短い…) and drill all six forms until they are automatic. Then move to the 10 most common na-adjectives (きれい, 静か, 有名, 便利, 大切, 大変, 丁寧…). Use the flashcard mode in this module to see the dictionary form, then flip to check all conjugations. Switch to quiz mode to test yourself under time pressure — the same pressure you will face in the JLPT exam hall.
This module contains 45 i-adjectives and 25 na-adjectives covering the full JLPT N5 and N4 adjective lists. All entries include English meaning, Bengali translation, and all major conjugated forms.