役に立つ (yakunitatsu) conjugation
to be helpful, to be useful
役に立つ (やくにたつ, yakunitatsu) is a godan verb. Godan verbs change their final kana up and down its column of the kana chart — the a-row for negatives, the i-row before ます, the e-row for potential and ば. Every form below is tappable — hear it, then say it back.
Conjugation table
| Form | Plain (casual) | Polite (~ます) | When you use it |
|---|---|---|---|
| Dictionary / plain | 役に立つ yakunitatsu | 役に立ちます yakunitachimasu | The form you look up. Also the casual present and future. |
| Plain negative | 役に立たない yakunitatanai | 役に立ちません yakunitachimasen | “doesn’t / won’t”. From here it conjugates like an i-adjective. |
| Plain past | 役に立った yakunitatta | 役に立ちました yakunitachimashita | The casual past — same ending as the te-form, with た/だ. |
| Plain past negative | 役に立たなかった yakunitatanakatta | 役に立ちませんでした yakunitachimasendeshita | “didn’t”. The negative past, still i-adjective-shaped. |
| Te-form | 役に立って yakunitatte | — | The connector: requests, linking clauses, ~ている. |
| Progressive (~ている) | 役に立っている yakunitatteiru | 役に立っています yakunitatteimasu | “is ~ing”, or an ongoing resulting state. |
| Desire (~たい) | 役に立ちたい yakunitachitai | 役に立ちたいです yakunitachitaidesu | “want to ~”. Behaves as an i-adjective. |
| Volitional | 役に立とう yakunitatou | 役に立ちましょう yakunitachimashou | “let’s ~” / “I think I’ll ~”. |
| Potential | 役に立てる yakunitateru | 役に立てます yakunitatemasu | “can ~”. What you could do; the object often takes が. |
| Passive | 役に立たれる yakunitatareru | 役に立たれます yakunitataremasu | “is ~ed”. Also the honorific and the suffering passive. |
| Causative | 役に立たせる yakunitataseru | 役に立たせます yakunitatasemasu | Make or let someone do it. |
| Causative-passive | 役に立たされる yakunitatasareru | 役に立たされます yakunitatasaremasu | Be made to do it — the long one. |
| Imperative | 役に立て yakunitate | 役に立ってください yakunitattekudasai | Blunt order. Use ~てください in real life. |
| Prohibitive | 役に立つな yakunitatsuna | — | “don’t!” — dictionary form + な. |
| Conditional (~ば) | 役に立てば yakunitateba | — | “if ~”. General rules and hypotheticals. |
| Conditional (~たら) | 役に立ったら yakunitattara | — | “if / when ~”. The everyday conditional. |
🔊 Tap any Japanese word to hear it spoken.
Why it conjugates this way
Godan verbs change their final kana up and down its column of the kana chart — the a-row for negatives, the i-row before ます, the e-row for potential and ば.
See the full rules on the verb conjugation guide.