Japanese Verb Conjugation: Godan, Ichidan, Irregular

One fact about Japanese verbs saves more study time than any other: every verb belongs to one of three groups, and the group decides every conjugation you will ever do. Sort a verb into the right group and the -masu, -te, -ta, -nai and potential forms all follow mechanically. Get the group wrong and every form after it is wrong too.

So the first skill is not memorising conjugations. It is classification. This page is the map — how to identify the group, what each group does to a verb's ending, and one fully conjugated verb per group to use as a template you can check anything against.

The three groups at a glance

The names are literal. 五段 (godan, "five rows") means the verb's last kana walks through five kana rows as it conjugates. 一段 (ichidan, "one row") means the ending stays put — you chop off る and attach things to what is left.

If your textbook says "group 1 / group 2 / group 3", that is the same three groups. Some textbooks swap the numbering of group 1 and group 2, which is a genuine source of confusion when you switch books. The names 五段 (godan) and 一段 (ichidan) do not move.

How to tell the group from the dictionary form

You only need the dictionary form — the plain form you find in a dictionary, like 書く (kaku, "to write") or 食べる (taberu, "to eat").

Step 1: is it する or 来る?

Then it is irregular, and no rule applies. This includes compounds: 勉強する (benkyou suru, "to study") and 持って来る (motte kuru, "to bring") inherit the irregularity of their second half.

Step 2: does it end in -eru or -iru?

If yes, it is probably ichidan. 食べる (taberu, "to eat"), 見る (miru, "to see"), 起きる (okiru, "to get up"), 寝る (neru, "to sleep"), 教える (oshieru, "to teach"), 覚える (oboeru, "to remember").

Be careful with what "ends in -eru" means. It means the final kana is る and the kana before it is from the え row or the い row — so べる, える, きる, みる. A verb like ある (aru, "to exist") ends in る but the kana before it is あ, from the あ row, so it is godan.

Step 3: everything else is godan

If the dictionary form ends in う, く, す, つ, ぬ, む, ぶ, ぐ, or る-not-preceded-by-e/i, it is godan. That is the default. When in doubt, guess godan.

The -eru / -iru verbs that are not ichidan

This is the single most common classification mistake, and it is worth meeting head-on: a few dozen common verbs end in -eru or -iru but behave as godan.

There is no rule that produces this list — it is a historical accident, and Japanese children learn the exceptions the same way you will, by meeting them. The list is short, so treat it as vocabulary rather than grammar. Anything you have not seen before and that ends in -eru or -iru is far more likely to be ichidan.

The five stems you will actually use

Every conjugation is a stem plus an ending. These are the five stems worth knowing by name.

The pattern inside that table is the whole trick:

• Godan changes its last kana. 書く walks く → き (masu) → い (te) → か (nai) → け (potential) → こ (volitional). That walk through the あ・い・う・え・お rows is why it is called five-row.
• Ichidan changes nothing. You remove る once and attach every ending to the same stem. 食べ + ます, 食べ + て, 食べ + ない, 食べ + られる.
• The two irregulars are memorised. They are only two verbs. It is a small bill to pay.

Here is the godan walk laid out, because seeing it once makes the whole group predictable:

Full conjugation table: one verb per group

This is the reference table. Print it, or come back to it whenever a form will not come out. One godan verb (書く, kaku, "to write"), one ichidan verb (食べる, taberu, "to eat"), and both irregulars.

Two things to notice. First, the ichidan potential and the ichidan passive are spelled the same — 食べられる is both "can eat" and "is eaten", and only context separates them. Godan keeps them apart: 書ける is potential, 書かれる is passive. Second, する is not just "to do" — it is the verb that turns nouns into verbs, so 勉強する, 掃除する and 説明する all conjugate exactly like する.

Three patterns that shrink the table

You do not have to memorise the table verb by verb. Three patterns generate almost all of it.

Godan's あ-row family. The -nai form, the passive, and the causative are all the same stem: 書か + ない, 書か + れる, 書か + せる. Learn one and you have three.

The -te and -ta forms are the same shape. 書いて / 書いた, 飲んで / 飲んだ. Only the final kana differs — て/で becomes た/だ. If you know the te-form rules, the ta-form is free.

Ichidan forms are all "stem + ending". The only real work is remembering which ending, and those endings are the same ones the other groups use.

The practical consequence is that you do not need to memorise the big table row by row. Learn the five stems, learn that godan walks through the rows while ichidan does not, and you can reconstruct any cell you forget. Reconstruction is what you actually need in conversation, anyway — nobody looks at a table mid-sentence.

Why the classification is not arbitrary

It can look like Japanese made the system complicated on purpose. It did not. The three groups are a snapshot of how the language changed over roughly a thousand years.

Ichidan verbs are the newer pattern: the verb's ending fused with the stem, so there is nothing left to change. Godan verbs preserved an older system in which the ending was a separate unit that moved. The two irregulars are the most common verbs in the language — する and 来る — and frequency is exactly what preserves irregularity, because children hear them too often to regularise them by mistake.

This is why the exceptions tend to be common verbs as well. 帰る, 入る, 知る and 行く are all high-frequency, and high frequency is where old forms survive.

Which order to learn them in

Frequency order, not table order:

1. -masu — the polite form you will speak with for your first year.
2. -te — the connector. Requesting, sequencing, and the te-iru progressive all need it.
3. -ta — plain past. You cannot tell a story without it.
4. -nai — the negative. See nai-form.
5. Potential, passive, causative — the られる / せる family, best learned together so you can see how they differ: potential and passive and causative.
6. -ba and volitional — conditionals and "let's", once the above are automatic.

Resist learning all ten at once. They are not equally common and the rare ones are not worth early confusion.

Common mistakes for English speakers

Guessing ichidan from -eru / -iru and being wrong. 帰る (kaeru) is godan, so it is 帰ります (kaerimasu), not 帰えます. If you learn one exception today, learn this one.

Using られる for a godan potential. 行かれる (ikareru) is not "can go" — it is the passive, "to be gone to". The godan potential is 行ける (ikeru, "can go"). Because ichidan verbs use られる for both, English speakers often over-generalise it to godan verbs where it means something else.

Expecting the verb to change with the subject. English says "I write / she writes". Japanese does not: 書く is correct for every person. There is no third-person -s, ever. The only thing that changes is politeness, and that changes the whole verb uniformly (書く → 書きます), never just one person's form.

Reading the plain form as present-only. 書く is both "I write" and "I will write". Japanese marks past and non-past; future is carried by context and by time words like 明日 (ashita, "tomorrow"). So 明日書く means "I will write tomorrow", not "I write tomorrow".

Treating です / ます as a tense. They are a politeness layer. 書きます and 書く describe the same event; only the social register differs.

Assuming "to" in an English gloss implies an infinitive. "To write" is a dictionary convention. Japanese has no infinitive, and no equivalent of "to" as a separate word.

Where this pays off

Classification is not a vocabulary exercise — it is the thing that makes everything downstream fast. Once you can say "godan" about a verb without hesitating, the correct form stops being a memory test and becomes arithmetic.

That only becomes automatic through repetition on real sentences, which is exactly what typing practice gives you: you produce 書きました (kakimashita) with your hands, get told immediately whether the ending was right, and the group membership gets encoded as a habit rather than a fact.

If you would rather see the kana before the grammar, the interactive kana chart covers every character with its romaji, and the romaji converter will romanise any sentence whose reading you are unsure of.

Practice verbs in full sentences, not in isolation — Romaji.live practice shows you a Japanese sentence, you type its romaji word by word, and every conjugation you get wrong is flagged on the spot. Work through the te-form rules next, since -te is the form the other conjugations lean on most.