Japanese Grammar

I-Adjectives vs Na-Adjectives

Unlike English, Japanese adjectives conjugate (change their endings) just like verbs. To do this correctly, you must first know if it's an i-adjective or a na-adjective.

The Two Types of Adjectives

In Japanese, every adjective belongs to one of two families: i-adjectives or na-adjectives.

I-adjectives always end in the Hiragana 'い' (i). For example: 大きい (ookii - big), 高い (takai - high/expensive). They change their own endings to express past or negative.

Na-adjectives act more like nouns. They require 'な' (na) to connect to other nouns, and they rely on 'です' (desu) to change into past or negative forms. For example: 静か (shizuka - quiet), きれい (kirei - beautiful).

Conjugation Rules

I-Adjectives (e.g., 高い - takai - expensive)

Present (+)

→高いです (takai desu)

It is expensive

Present (-)

→高くないです (takaku nai desu)

Change 'i' to 'ku nai'

Past (+)

→高かったです (takakatta desu)

Change 'i' to 'katta'

Past (-)

→高くなかったです (takaku nakatta desu)

Change 'i' to 'ku nakatta'

Na-Adjectives (e.g., 静か - shizuka - quiet)

Present (+)

→静かです (shizuka desu)

It is quiet

Present (-)

→静かじゃありません (shizuka ja arimasen)

Change desu to ja arimasen

Past (+)

→静かでした (shizuka deshita)

Change desu to deshita

Past (-)

→静かじゃありませんでした (shizuka ja arimasen deshita)

Past negative

Connecting to Nouns

I-adjective + Noun

→高い車 (takai kuruma)

Just put it before the noun

Na-adjective + Noun

→静かな部屋 (shizuka na heya)

MUST add 'na' between them

Tricky Exceptions

きれい (kirei)

Beautiful / Clean

Ends in 'i', but is actually a NA-adjective! -> きれいな部屋 (kirei na heya)

有名 (yuumei)

Famous

Ends in 'i', but is a NA-adjective! -> 有名な人 (yuumei na hito)

嫌い (kirai)

Dislike

Ends in 'i', but is a NA-adjective! -> 嫌いな食べ物 (kirai na tabemono)

Teacher's Advice

General Advice

The most common mistake beginners make is conjugating 'いい' (ii - good). 'いい' is irregular! To make it negative or past, it changes to 'よい' (yoi) first. So 'not good' is 'よくない' (yoku nai), and 'was good' is 'よかった' (yokatta). NEVER say 'ikunai' or 'ikatta'!

JLPT Exam Patterns

•Conjugating exceptions like きれい and 有名 correctly (N5)
•The irregular conjugation of いい (yokunai, yokatta) (N5)
•Connecting adjectives (I-adj: dropping 'i' + 'kute', Na-adj: adding 'de') (N5)

Master Adjectives

Use our interactive quiz to drill the difference between i-adjectives and na-adjectives.

Start Quiz →