Godan and ichidan verbs

Godan and Ichidan Verbs: The Two Regular Classes

Japanese verbs fall into two regular classes: 五段（ごだん） (godan, "five-row") and 一段（いちだん） (ichidan, "one-row"). These names come from the number of vowel rows they use in their conjugation patterns. Together they cover the vast majority of verbs, with only a few irregular verbs like する and 来る（くる） outside them.

Why Spelling Doesn't Tell You the Class

A common frustration for learners is that you cannot reliably tell a godan verb from an ichidan verb just by looking at its dictionary form. For example, 帰る（かえる） (to return) is godan, while 食べる（たべる） (to eat) is ichidan. Both end in -eru. Similarly, 切る（きる） (to cut) is godan, but 見る（みる） (to see) is ichidan. The dictionary form alone is ambiguous.

The only way to know for certain is to check the conjugation or memorize the class. Some patterns help: verbs ending in -u (not -ru) are always godan, and most verbs ending in -iru or -eru are ichidan, but there are many exceptions. For instance, 入る（はいる） (to enter) and 知る（しる） (to know) are godan despite ending in -iru.

How Godan Verbs Conjugate

Godan verbs change their final u-vowel sound across all five vowel rows: a, i, u, e, o. The stem is the part before the final u. For example, for 書く（かく） (to write), the stem is kak.

Here are the basic forms for 書く（かく）:

• Negative: 書かない（かかない） (stem + -anai)
• Masu-form: 書きます（かきます） (stem + -imasu)
• Dictionary form: 書く（かく） (stem + -u)
• Conditional: 書けば（かけば） (stem + -eba)
• Volitional: 書こう（かこう） (stem + -ou)

Notice how the final vowel shifts: a in the negative, i in the masu-form, u in the dictionary form, e in the conditional, and o in the volitional. This is why it is called "five-row" — it uses all five vowel rows.

How Ichidan Verbs Conjugate

Ichidan verbs always end in -iru or -eru and drop that final -ru to form the stem. For example, for 食べる（たべる） (to eat), the stem is tabe. The conjugation is simpler because the stem does not change; you just add endings.

Here are the basic forms for 食べる（たべる）:

• Negative: 食べない（たべない） (stem + -nai)
• Masu-form: 食べます（たべます） (stem + -masu)
• Dictionary form: 食べる（たべる） (stem + -ru)
• Conditional: 食べれば（たべれば） (stem + -reba)
• Volitional: 食べよう（たべよう） (stem + -you)

Because the stem remains constant and only the ending changes, ichidan verbs are called "one-row" — they use only one vowel row.

Distinguishing the Two Classes

To identify a verb's class, you can use the negative form or the masu-form. For example, the negative of 帰る（かえる） is 帰らない（かえらない） (godan), while the negative of 食べる（たべる） is 食べない（たべない） (ichidan). The presence of -anai (with an a) indicates godan, while -nai (without a) indicates ichidan. Similarly, the masu-form of 帰る is 帰ります（かえります） (godan), and the masu-form of 食べる is 食べます（たべます） (ichidan); the extra i in -imasu vs. -masu is the clue.

Another test is the -ba conditional: godan uses -eba (e.g., 書けば), while ichidan uses -reba (e.g., 食べれば).

Common Exceptions and Irregularities

Some verbs that look like ichidan are actually godan. These include 帰る（かえる）, 切る（きる）, 知る（しる）, 入る（はいる）, 走る（はしる）, and 要る（いる） (to need). They conjugate with godan patterns, so their negative forms are 帰らない, 切らない, etc.

There are also a few verbs that are irregular in some forms, such as ある (to exist, godan but with irregular negative ない) and くれる (to give, ichidan but with irregular imperative くれ).

Why This Matters

Getting the verb class right is crucial because it determines all subsequent conjugations, including the te-form, past tense, and potential form. For example, the te-form of 書く is 書いて (godan, with a sound change), while the te-form of 食べる is 食べて (ichidan, no change). A mistake in class leads to incorrect forms.

For practice, you can use conjugation drills and games, such as the Conjugation Dojo, to build speed and accuracy. The grammar library also has detailed lessons on each conjugation pattern.

Summary

In short, godan verbs conjugate by changing the final vowel across five rows, while ichidan verbs keep a stable stem and simply add endings. The dictionary form does not reliably indicate the class, so you must learn each verb's class or check its conjugation. With practice, recognizing the class becomes automatic.