Learn Hardcore Japanese: koko ha kinen da kara, soto nara daizyoubu desu. - It’s non-smoking here, so outside is okay.

なら marks a conditional based on a given option or context: “as for outside / if it’s outside (that option), [it’s fine].” It often picks one case out of several possibilities and comments on it.

Differences:

なら: conditional tied to a topic or previously mentioned idea. As for X, Y. 外なら大丈夫です = As for outside, it’s okay.
たら: event/temporal “if/when.” 外に出たら大丈夫です = Once you go outside, it’ll be okay.
と: logical/result or habitual condition; too stiff for this nuance.

Why is there だ before から in 禁煙だから?

禁煙 is a noun. When a noun or na-adjective directly precedes から in plain style, you need the copula だ:

Noun + だ + から: 禁煙だから (because it’s non-smoking)
Na-adjective + だ + から: 静かだから (because it’s quiet)

If you want to stay fully polite there, use ですから: 禁煙ですから.

Is it okay to mix plain だ and polite です in the same sentence?

Yes, very common. Subordinate clauses (like …から) often use plain form, while the sentence ends politely: ここは禁煙だから、外なら大丈夫です。 If you prefer full politeness, use: ここは禁煙ですから、外なら大丈夫です。

Could I use ので instead of から? Any nuance difference?

Yes:

ここは禁煙なので、外なら大丈夫です。
ここは禁煙ですので、外なら大丈夫です。 (more polite)

Nuance: ので sounds a bit softer and more explanatory; から is more direct and conversational.

Why is it ここは and not ここで?

は marks the topic “as for here,” describing a property of the place (it’s non-smoking). If you want to emphasize the location where an action happens, use ここで (place of action). For example:

Property: ここは禁煙です。 (This place is non-smoking.)
Action/location: ここではタバコを吸えません。 (You can’t smoke here.)

Is ここでは禁煙 also natural?

You’ll hear and see it, but ここは禁煙です is the most straightforward way to state the property of the place. Use ここでは when you’re focusing on actions taken “in this location,” e.g., ここでは喫煙できません.

Why is there no particle after 外 in 外なら?

なら attaches directly to nouns, so no extra particle is required. If you want to stress the location-of-action, you can say 外でなら (as for doing it outside, it’s okay). Both 外なら and 外でなら are natural; the latter makes the “place of doing it” extra clear.

What exactly does 大丈夫です mean here?

大丈夫です means “It’s okay / it’s no problem.” In this context, it conveys permission/acceptability. Alternatives:

外なら構いません。 (I don’t mind if it’s outside; more formal-ish)
外ならOKです。 (casual/loanword)
More explicit permission for the action: 外なら吸ってもいいです。 (It’s okay to smoke if it’s outside.)

If I want to be explicit about smoking, how do I say it?

Add the action:

外ならタバコを吸っても大丈夫です。
外ならタバコを吸ってもいいです。
ここは禁煙なので、タバコは外でお願いします。 (As a request)

How do you read 禁煙 and what does it literally mean?

Read: きんえん (kin’en). Literally “prohibit” (禁) + “smoke” (煙) → “no smoking.” Related words:

喫煙 (きつえん): smoking
禁煙席: non-smoking seat
喫煙所: smoking area

Could I say 喫煙禁止 instead of 禁煙?

Yes, 喫煙禁止 (smoking prohibited) is fine, but it sounds more formal/sign-like. 禁煙 is the most common, concise label. For polite speech to a customer, a full sentence like ここは禁煙です is natural.

How polite/formal is the original sentence? What’s a more formal version?

Original is polite but conversational. More formal/honorific toward customers:

こちらは禁煙でございます。喫煙される場合は外でお願いいたします。 Slightly softer formal:
ここは禁煙ですので、喫煙は外でお願いいたします。

Can I reorder the clauses?

You can, but reason-first is more typical with から/ので:

ここは禁煙だから、外なら大丈夫です。 (most natural) If you put the reason second, it can sound tagged-on:
外なら大丈夫です。ここは禁煙だから。 (casual; okay in speech) Using ので makes end-reasons sound a bit more natural: 外なら大丈夫です。ここは禁煙なもので。

What’s the difference between 外なら and 外だったら?

Both can work. なら is lean and “topic-conditional” (“as for outside”). だったら can feel a bit more hypothetical or responsive to prior context (“if it were outside/if that’s the case, then…”). In neutral statements of permission, 外なら is slightly crisper.

Would いい be better than 大丈夫 for permission?

Use 〜てもいい for explicit permission of an action; 大丈夫です is broader (“it’s fine/no problem”). For maximum clarity:

外ならタバコを吸ってもいいです。 (You may smoke outside.)
外ならタバコを吸っても大丈夫です。 (It’s okay to smoke outside.) Both are accepted; 〜てもいい is the textbook “may” pattern.

Are spaces normal in Japanese? What about the comma?

Spaces are not used in regular Japanese writing; they’re just for learners. The sentence would normally be: ここは禁煙だから、外なら大丈夫です。 The comma 、 correctly separates the reason clause from the main statement.

Is there a very casual way to say this?

Yes, dropping particles and politeness:

ここ、禁煙だから、外なら大丈夫。
ここ禁煙ね。外ならOK。