〜たらいい: 'It Would Be Good If...' (Meaning + Examples)
Expressing a hope or wish
〜たらいい says that a hypothetical situation would be a good one — often used to express a wish about something that isn't currently true, especially with 〜のに at the end.
やったんは、もっと時間があったらいいのになあ、と思った。
やったんは、もっと じかんが あったらいいのになあ、と おもった。
Yattan thought, 'I really wish there were more time.'
あったらいいのに = a wistful wish for something not currently true.
モチと毎日遊べたらいいのに。
モチと まいにち あそべたらいいのに。
I wish I could play with Mochi every day.
Asking for advice: どうしたらいいですか
In question form, 〜たらいい becomes a common, polite way to ask what to do — literally "if I do what, would it be good?"
この問題、どうしたらいいですか。
このもんだい、どうしたらいいですか。
What should I do about this problem?
どうしたらいいですか is one of the most common ways to ask 'what should I do?'
分からなかったら、先生に聞いたらいいよ。
わからなかったら、せんせいに きいたらいいよ。
If you don't understand, you should just ask the teacher.
Here たらいい gives friendly advice rather than expressing a wish.
Attaching to the た-form
〜たらいい attaches to a verb's た-form (the same stem as the たら conditional), followed directly by いい, or いいのに for a wish about an unreal situation.
| Verb group | た-form | +たらいい |
|---|---|---|
| う-verb (聞く) | 聞いた | 聞いたらいい |
| る-verb (食べる) | 食べた | 食べたらいい |
| する/来る | した／来た | したらいい／来たらいい |
Don't confuse with 〜ばいい
〜ばいい (the ば-conditional + いい) means almost the same thing and is interchangeable in most advice contexts — どうすればいいですか ≈ どうしたらいいですか. たらいい tends to sound a touch more conversational, while ばいい is slightly more common in written advice columns, but the difference is subtle enough that either works in casual speech.
The short version
- 〜たらいい = "it would be good if / I wish" (statement); "what should I do?" (question, どうしたらいいですか).
- Attaches to: verb た-form + いい (or + いいのに for a wistful wish).
- Nuance/register: casual, common in spoken advice and wishes.
- Don't confuse with: 〜ばいい, a near-synonym using the ば-conditional instead of たら.
Practice it
Choose たらいい when the sentence expresses a wish or asks/gives advice about what to do.
＿＿＿に入れるのに最もよいものを選びなさい。
もっと時間が＿＿＿のに。
Where 〜たらいい fits
Shaky on this? Get these solid first
- Conditional 〜たら · N4 — 〜たら is Japanese's most flexible conditional: just add ら to the plain past. Learn the formation, the 'if/when' meaning, the discovery use, and how it beats ば/と for requests.
- Past Tense · N5 — The plain past た-form means 'did.' It follows the same sound changes as the て-form (just て→た, で→だ): 食べた, 行った, 飲んだ. Learn it by verb group.
More N3 grammar to explore
Keep going with related patterns at the same level:
- 〜てもかまわない — 〜てもかまわない attaches to the て-form to grant permission or express indifference — ここで吸ってもかまいません ('it's fine to smoke here'). Slightly more formal than 〜てもいい, and literally says 'even if..., it doesn't bother me.'
- 〜としたら — 〜としたら means 'if we suppose/assume that...' — it sets up a hypothetical premise and asks what follows from it. Common with もし and questions about what you'd do in that case.
- なぜなら — なぜなら(ば) and なぜかというと state the reason for a previous sentence in a fresh sentence that closes with 〜からだ. Learn the pattern, register, and how it differs from から/ので.
- 〜によって — 〜によって is a versatile N3 pattern: means/method, 'varies depending on,' formal cause, and the agent in passive sentences. Learn all four senses plus による and によっては.
- 〜おかげで — 〜おかげで means 'thanks to' — a cause with a positive, grateful result: 先生のおかげで合格できた. Learn the formation, the set phrase おかげさまで, and how it contrasts with せいで.
- 〜せいで — 〜せいで assigns blame: it marks a cause that led to a NEGATIVE result. Learn のせいで, せいか (maybe because), せいにする (to blame on), and せいで vs おかげで.