The Three Verb Groups
Japanese verbs fall into three groups, and every form depends on knowing which group a verb belongs to. Get the group right and the conjugation is mechanical; get it wrong and every form will be wrong.
The -eru / -iru trap
Most verbs ending in -eru or -iru are ichidan, but not all. 帰る (kaeru), 入る (hairu), 走る (hashiru), 切る (kiru), 知る (shiru), 要る (iru), 限る (kagiru), 滑る (suberu) and 減る (heru) are godan. If a verb does not behave as expected, check it once and remember it as an exception.
The Master Chart
One godan verb, one ichidan verb, and both irregulars across the forms you actually need. Learn this grid and the rest is substitution.
Notice that the ichidan column only ever removes る and adds an ending. The godan column changes the final vowel: 書く moves through か / き / く / け / こ.
The Masu Form
The polite form is what you use with strangers, teachers, colleagues and anyone you do not know well. For godan verbs, the final u-sound becomes an i-sound and ます is added; for ichidan verbs, る simply becomes ます.
The Te-Form
The te-form has no single English equivalent. It links clauses, makes requests (〜てください), describes ongoing states (〜ている), and forms dozens of patterns. It is the single most useful form in the language.
て and た move together
Every te-form rule has an identical ta-form rule with た instead of て. Learn them as one pair and you halve the memorisation.
The Nai Form
The plain negative is the base of casual speech and of several important patterns. Godan verbs shift to the a-row and add ない; ichidan verbs drop る and add ない.
One exception worth knowing immediately: ある (to exist) negates as ない, not あらない.
Nai-form patterns
Common Mistakes
Check your conjugation in writing
Paste a short paragraph into the Lingaso writing analyser to see which forms are misfiring — usually it is one group, not all three.Practice
Convert each verb into the form requested, then check against the chart.
- 飲む → masu, te, nai
- 見る → masu, ta, nai
- 待つ → te, ta, potential
- 来る → masu, te, nai
- する → potential, volitional, causative
If you are still choosing groups by feel, work through the N5 plan first — verb groups are assumed knowledge from N5 onwards.
FAQ
How do I know if a verb is godan or ichidan?
If the dictionary form ends in anything other than -eru or -iru, it is godan. If it ends in -eru or -iru it is usually ichidan, but a set of common verbs are exceptions, including 帰る, 入る, 走る, 切る and 知る.
What is the difference between the masu form and the dictionary form?
The masu form is polite and used with people you do not know well, in service situations, and in most written communication. The dictionary form is the plain form used with friends, family and in casual writing; it is also the form you look up in a dictionary.
Why does the te-form have so many patterns?
Because it does several jobs at once: linking clauses, making requests with ください, forming the progressive with いる, and building dozens of grammar patterns. That is why it is worth learning early and practising until it is automatic.
Are there really only two irregular verbs?
Yes — する and 来る are the only fully irregular verbs. 行く has an irregular te-form (行って), and ある has an irregular negative (ない), but these are single exceptions rather than irregular conjugations.