The below grammar is JLPT N4 & N3. The core conditionals (〜たら, 〜ば, なら, と) are N4 level, while the hypothetical structures (〜とすると, 〜とすれば, 〜としたら) are N3 level.
There are five main ways to form the conditional in Japanese and each has its own nuance or prescribed usage.
Ending
Conditional Form
〜たら
The General Case
〜ば
The Strong Conditional
なら
Basis
とすると
The Hypothetical
と
Natural Consequences
You can think of all but the last as being closely related—the nuance is in the degree to which you wish to stress the conditionality of the sentence.
In English we make a fairly clear distinction between “when” and “if”.
When I get home I’m going to make hot chocolate.
If I get home I’m going to make hot chocolate.
In Japanese the difference is not so well defined. For example, we could translate 〜たら as “when” or “if” depending on the context.
The conditional form using と is used to express a natural consequence of A—not an action that you will take. We will look at each of these in more detail.
The General Case (～ら)
Core JLPT N4 grammar. The 〜たら form of the conditional is the most common and the safest for learners precisely because it is so universally applicable.
Verbs
To create the 〜たら conditional for all verbs we simply take the standard past tense or negative and add ら.
Verb
Dictionary
+ve Conditional
-ve Conditional
to say
言う
言ったら
言わなかったら
to come back
戻る
戻ったら
戻らなかったら
to see
見る
見たら
見なかったら
to do
する
したら
しなかったら
仕事が早く終わったら、飲み会に参加する。
If my work finishes early I will join for drinks.
出張で京都に行ったら金閣寺の写真を撮る。
If I go to Kyoto on a business trip I will take a photo of the kinkaku-ji.
今夜、家に帰ったらビールを飲んでテレビを見ます。
Tonight when I get home I’ll drink a beer and then watch television.
So how do we know whether 〜たら means “when” or “if”? Well, you often know from the context of the sentence. Let’s look again at the first example sentence above. If we translate the conditional as “when” it sounds strange: “When work finishes early I will join for drinks” (we don’t know for a fact that we will finish early). Equally, in the last sentence it’s reasonable to assume that you’re going to get home at some point so “when” is probably a more natural translation.
わからなかったら声をかけてください。
Give me a shout if you don’t understand.
金曜日だったらいいですね。
I wish it were Friday.
This way of creating the conditional is not limited to the standard past tense, we can also use it with the potential form, as well as the causative and passive forms which will be introduced later.
漢字が読めたら、日本で働けると思いますよ。
If you can read kanji then I think you can work in Japan.
Adjectives
We can change adjectives following exactly the same rules.
Adj.
Dict.
+ve Conditional
-ve Conditional
interesting
面白い
面白かったら
面白くなかったら
easy
簡単
簡単だったら
簡単ではなかったら
成績が良かったら食事に行ましょう。
If your grades are good let’s go for dinner.
部屋が寒かったら、眠れない。
If the room is cold I won’t be able to sleep.
The Stronger Conditional (～ば)
JLPT N4 grammar. Unlike 〜たら, 〜ば places more emphasis on the possibility that the first clause might not happen and, as such, is usually translatable as “if”.
Verbs
The 〜ば affirmative conditional ending is formed for all verbs by changing the “u” ending to an “e” ending syllable on the same row and adding ば.
する → すれ＋ば → すれば
For the negative conditional we replace the ending ない with なければ.
する → しない → しなければ
Verbs
Dictionary
+ve Conditional
-ve Conditional
to ask
聞く
聞けば
聞なければ
to go home
帰る
帰れば
帰らなければ
to see
見る
見れば
見なければ
to do
する
すれば
しなければ
お酒を飲めば、眠くなる。
If I drink alcohol I get sleepy.
また機会があれば一緒に旅行ましょうね。
Let’s go on holiday together if we get another chance.
終電に間に合なければ、泊まってもいいですか。
If I miss the last train can I stay the night?
The 〜ば conditional is very often used to form a “What should I do?” type of question.
何を注文すればいいですか？
What should I order?
彼女に会ったら何を言えばいいですか？
When I meet her what should I say?
Like with 〜たら we can also change the potential form of the verb.
金曜日までに回答が得られれば大変ありがたいです。
If I could get an answer by Friday it would be very much appreciated.
パスタでも作れなければティラミスは無理だね。
If you can’t even make pasta then Tiramisu is out of the question.
For the auxiliary verb, we need to use the literary form. We have three forms of the auxiliary verb:
Verbs
Dictionary
Polite
Literary
to be
だ
です
である
In terms of conjugation, you can think of the literary form of the verb as simply で and the verb ある, for which we already know the conjugation. Consequently, to form to the 〜ば conditional we follow the above rules to get であれば for the affirmative and でなければ for the negative.
到着日が週末であれば迎えに行けると思います。
If you’re arriving at the weekend then I think I will be able to collect you.
彼は先生でなければ誰ですか？
If he isn’t a teacher, then who is he?
Adjectives
For i-adjectives, we change the い into ければ.
Adjective
Dictionary
+ve Conditional
-ve Conditional
Light
軽い
軽ければ
軽くなければ
Heavy
重い
重ければ
重くなければ
この番組が面白くなければチャンネルを変えてもいいですよ。
If this TV programme isn’t interesting you can change the channel.
“You can change the channel” is a more natural translation of the literal “even if you change the channel it’s good”.
For na-adjectives, as you’ve probably worked out, we need the literary form of the auxiliary verb introduced above.
火曜日が無理であれば他の日を見つけよう。
If Tuesday is impossible let’s find another day.
パスポートも必要であれば明日に持ってきます。
If my passport is also required I will bring it tomorrow.
A Basis for a Statement (～なら)
JLPT N4 grammar. なら places a much stronger emphasis on A being a condition to B. A close literal translation might be: “On the basis that the situation A exists, then B will occur/be true.” Unlike the previous conditionals, there is no need to alter verb forms or remember any particular rules—you simply add なら to the dictionary form of the verb, adjective, or noun. Simple.
君ならできるよ。
I know you have it in you.
明日は飲み会があるけど、来られるなら嬉しいです。
We’re having drinks tomorrow. I’d be happy if you could make it.
Note that the but conjunction is being used to introduce the topic of drinks to the conversation and would not get translated as “but” in English.
課長がオッケーと言うなら今日は早く帰りましょう。
If the department boss says it’s okay then let’s go home early today.
In Japanese companies more senior employees are often referred to by their title rather than their name.
弟とけんかしないと約束するなら遊園地に連れていくよ。
If you promise not to fight with your little brother I’ll take you both to the amusement park.
You may see ば added to this form of the conditional. This does not change the meaning—it is merely another form of なら.
あまりにも恥ずかしいならば、発表しなくてもいいですよ。
If it’s really too embarrassing, you don’t have to make the presentation.
あまりにも looks like あまり but actually means something quite different. It comes before adjectives to mean “too much”, often with a negative connotation.
Natural Consequences (～と)
JLPT N4 grammar. Where 〜たら, 〜ば and 〜なら preceded actions, と precedes a natural consequence (not typically an action that you will take).
A Critical Rule: Because it represents a natural, inevitable consequence, the second half of a と sentence cannot contain a command, request, suggestion, or expression of the speaker’s will. (e.g. “If you turn right, go to the store” is incorrect with と. You must use たら or ば instead). This limitation is very frequently tested on the JLPT.
と attaches itself to the dictionary form of the verb.
グラスが落ちると割れます。
If glass falls it will break.
テレビを消すと静かになります。
If you turn off the TV it will become quiet.
However, it doesn’t have to be such a physically natural consequence; と can be used to imply that something always happens as if it were a natural consequence.
試験が終わると、習ったことをすぐに忘れます。
Once exams have finished I immediately forget what I learnt.
The following, however, would be strange since going shopping with your friend is not a generally accepted truth upon finishing exams.
試験が終わると、友達と買い物に行きます。(✘)
Once exams have finished I will go shopping with my friend.
In this case the 〜たら form would be the better conditional form.
発車サイン音が鳴り終わるとドアが閉まります。
Doors close soon after the melody ends.
明日は天気が晴れるといいですね。
It would be nice if it’s sunny tomorrow.
〜といいですね is a common way of saying, “It would be nice if…” and is likely to appear on the JLPT N4 examination.
For the auxiliary verb we add と to the standard form だ.
成績が６０点以上だと合格になります。
60 points and above is a pass.
Adjectives
I-adjectives follow the same rules: just add the と particle after the dictionary form of the adjective. Na-adjectives take the auxiliary verb as above.
映画が面白いといいですね。
Hopefully the film is good.
The Hypothetical (とすると)
JLPT N3 grammar. Whereas the other forms of the condition mainly differ based on the level of conditionality, とすると is used to present a purely hypothetical situation. In this sense, it is close to “were” and “would” in English. The structure uses と to append the verb “to do” to the prior verb. This “to do” verb is then changed into the conditional, giving us three possible structures.
〜としたら
〜とすれば
〜とすると
You don’t tend to see とするなら very often so I’ve omitted it as an option from above.
Essentially, we use the same grammar as we learnt for the other conditionals but “double-up” on the verb. The nuance is identical for all three; although, at a push, you could argue that とすれば tends to be used more after nouns and adjectives.
留学するとしたら、イギリスに行くだろう。
If I were to study abroad I suppose I would go to the U.K.
もしそれが事実だとすればやめるでしょう。
Assuming that it’s true I guess I’ll resign.
時間を遡ることができるとすればいつの時代にする？
If you could go back in time to which era would you choose?
特に不自然なところはないけど、直すとしたらこの文章を二つに分けるでしょう。
There’s nothing particularly unnatural, but if I were to correct it I suppose I’d break the sentence into two.
全ての条件が同じだとすると、日本人は日本製の製品を好む。
All else being equal, the Japanese prefer Japanese-made products.
What about Moshi?
Many textbooks will introduce the conditional along with もし and consequently learners begin to associate this word with “if”. As we have seen, you do not need もし to form the conditional. So what does it do? Well, like how 〜たら, 〜ば and 〜なら express different levels of conditionality, もし merely emphasises the uncertainty of A happening in the first place or of B being a condition of A. It is placed before the conditional clause like so:
もし日本語が勉強したいと思っていたら教えますよ。
If you’re thinking you want to study Japanese then I’ll teach you.
もし京都に行くなら、深夜バスで行くのが一番安いです。
If you’re going to go to Kyoto the night bus is the cheapest way.