Conjugation is the rules for transforming a verb's dictionary form into other forms — past, negative, polite, requesting, continuous, and on. Japanese has a lot of forms, but the rules are mostly mechanical, and the patterns repeat. This guide covers the four conjugations you'll meet first; later guides go deeper.
For each form below, we'll show the rule, then a comparison across the three verb groups (ru-verb, u-verb, irregular). Bookmark this page and come back to it; nobody learns conjugation from one read-through.
The polite form (-masu)
The form you'll use in nine out of ten conversations as a beginner. Safe in any social context. Built by attaching ます to the verb's "stem."
| Group | Rule | Example |
|---|---|---|
| Ru-verb | Drop る, add ます | 食べる → 食べます |
| U-verb | Shift う-row final → い-row, add ます | 書く → 書きます |
| する | Memorize | する → します |
| 来る | Memorize | 来る (kuru) → 来ます (kimasu) |
The "u-row to i-row" shift means: take the last kana of the dictionary form and move it up the gojūon. く (ku) → き (ki). す (su) → し (shi). む (mu) → み (mi). And so on.
The four polite forms
From the -masu base, the other tense/polarity forms are completely regular for every verb:
| Tense / polarity | Ending | Example |
|---|---|---|
| Present (positive) | ます | 食べます (eat / will eat) |
| Past (positive) | ました | 食べました (ate) |
| Present (negative) | ません | 食べません (do not eat) |
| Past (negative) | ませんでした | 食べませんでした (did not eat) |
That's it. Once you have the -masu base for any verb, all four polite forms come for free.
The casual present and past
Casual is the form used in dialogue between friends, family, internal thought, and a lot of media. The rules diverge between ru-verbs (easy) and u-verbs (rule per consonant ending).
Ru-verbs — easy
Drop the る, add the ending. Past tense is た, negative is ない, past-negative is なかった.
| Tense | Form | Example (食べる, taberu) |
|---|---|---|
| Present | dictionary form | 食べる (eat) |
| Past | stem + た | 食べた (ate) |
| Negative | stem + ない | 食べない (do not eat) |
| Past negative | stem + なかった | 食べなかった (did not eat) |
U-verbs — rule per ending
U-verbs have a beautifully regular but slightly memorization-heavy past tense. The final kana of the dictionary form determines which past-tense ending is used. This is the famous ta-form table — once you know it, the te-form follows identical rules with て instead of た.
| Ending | Past | Example |
|---|---|---|
| う / つ / る | った | 買う → 買った (kau → katta) |
| ぬ / ぶ / む | んだ | 飲む → 飲んだ (nomu → nonda) |
| く | いた | 書く → 書いた (kaku → kaita) |
| ぐ | いだ | 泳ぐ → 泳いだ (oyogu → oyoida) |
| す | した | 話す → 話した (hanasu → hanashita) |
And one absolute exception: 行く (iku, "to go") is irregular and goes 行った (itta), not the predicted ★行いた.
U-verb negatives — change う-row to あ-row, add ない
Slide the final kana down the column, then add ない: 書く (ka-ku) → 書か (ka-ka) → 書かない (kakanai, "do not write"). One subtlety: verbs ending in う shift to わ, not あ: 買う (kau) → 買わない (kawanai), not ★買あない.
| Verb | Negative | Reading |
|---|---|---|
| 書く | 書かない | kaku → kakanai |
| 飲む | 飲まない | nomu → nomanai |
| 話す | 話さない | hanasu → hanasanai |
| 買う | 買わない | kau → kawanai |
And one more exception: the verb ある ("to exist, inanimate") doesn't have a negative ★あらない — its negative is just ない.
The te-form (〜て)
The single most important form in Japanese. Why? Because it's a connector. The te-form by itself doesn't mean much, but dozens of grammar patterns hang off it: requests, ongoing actions, listing actions, asking permission, giving permission, forbidding things, "if" conditionals, and more.
The good news: the te-form follows the same rules as the past tense (ta-form), but with て instead of た.
| Group / Ending | Te-form | Example |
|---|---|---|
| Ru-verb | stem + て | 食べる → 食べて |
| U-verb う/つ/る | って | 買う → 買って |
| U-verb ぬ/ぶ/む | んで | 飲む → 飲んで |
| U-verb く | いて | 書く → 書いて |
| U-verb ぐ | いで | 泳ぐ → 泳いで |
| U-verb す | して | 話す → 話して |
| する | して | する → して |
| 来る | 来て (kite) | 来る → 来て |
What you do with te-form
A short tour of the most common patterns. Each is a separate grammar point you'll learn later, but knowing the te-form is the gate that unlocks all of them.
| Pattern | Example | Meaning |
|---|---|---|
| 〜てください | 食べてください | Please eat |
| 〜ている | 食べている | Is eating (continuous / habitual) |
| 〜てもいいですか | 食べてもいいですか | May I eat? |
| 〜てから | 食べてから | After eating |
| 〜て、〜 | 食べて、寝る | Eat and (then) sleep |
When you hear someone say "the te-form is the most important conjugation in Japanese," this is why. Master the conversion rules early and you can take advantage of every pattern listed above as you encounter them.
The negative te-form (〜なくて / 〜ないで)
Two competing forms. They're easy to mix up.
- 〜なくて — used for "and not" / "because not." 食べなくて... ("not eating, and...").
- 〜ないで — used for "without doing" or "instead of doing." 食べないで寝る ("sleep without eating").
Both come from the negative form (〜ない). Replace the い with くて or で. You'll meet both in beginner-level material; pay attention to which one each sentence pattern uses.
What we left out
A complete tour of Japanese conjugation includes the potential form (can do), passive (be done), causative (make do), conditional (-eba, -tara), volitional (let's do, intend to), imperative (do! — rude), and more. Each is a future grammar lesson. With the polite forms, casual forms, and te-form locked in, you have the foundation that every other form is built on top of.