Posted on by Tae Kim

Conditional

There are four ways to express conditional in Japanese, each with a slightly different meaning and used in different situations.

General Conditional

The most generic conditional without any assumptions or embedded meanings is the 「～ば」 conditional. The conjugation rules for the 「ば」 conditional is below.

Conjugation rules for 「ば」

  • For verbs: change the last /u/ vowel sound to the /e/ vowel sound and append 「ば」
    Example

    1. 食べる　→　食べれ → 食べれ＋ば = 食べれば
    2. 待つ　→　待て → 待て＋ば = 待てば
    3. する　→　すれ → すれ＋ば = すれば
  • For i-adjectives and negatives ending in 「ない」: drop the last 「い」 and append 「ければ」
    Example

    1. おいしい　→　おいし＋ければ = おいしければ
    2. 食べない　→　食べな＋ければ = 食べなければ
    3. ない　→　な＋ければ = なければ
  • For nouns and na-adjectives: append 「であれば」
    Example

    1. 学生　→　学生であれば
    2. 暇　→　暇であれば

Example

  1. 早めに電話すれば、予約が簡単にできるよ。
    If (you) call early, (you) can make (a) reservation easily.
  2. 明日は忙しくなければ、映画を見に行かない？
    If tomorrow is not busy, won’t (you) to go to watch movie?
  3. 親切な人であれば、友達になれると思う。
    If (he/she) is (a) nice person, (I) think (we) can become friends.

Past Conditional

The past conditional is created by adding 「ら」 to the past tense form of a verb, noun, or adjective. The full form is 「らば」 but the 「ば」 is usually omitted.

This form can also used in the past tense to describe something that was unexpected instead of a condition.

Past conditional conjugation rule
Change the noun, adjective, or verb to its past tense and append 「ら（ば）」
Example

  1. 友達だった＋ら = 友達だったら
  2. 忙しかった → 忙しかった＋ら = 忙しかったら
  3. 食べた → 食べた＋ら = 食べたら
  4. 読んだ → 読んだ＋ら = 読んだら
  5. 暇じゃなかった＋ら = 暇じゃなかったら

Example

  1. 今日は忙しかったら、明日会いましょう。
    If (you) are busy today, let’s meet tomorrow.
  2. 行きたくなかったら、どうして行きたいと言ったの？
    If (you) didn’t want to go, why did (you) say (you) wanted to go?
  3. 家に帰ったら、犬がごみを散らかしていた。
    When (I) returned home, (the) dog was scattering around (the) garbage.

Contextual conditional

The contextual conditional is used by appending 「なら（ば）」 to a noun, verb, or adjective. The full form is 「ならば」 but the 「ば」 is usually omitted.

This conditional is used to describe something in a given context. Often, there is no actual conditional, ie “Well, if that’s the case, then…” or “Given that…”

Contextual conditional usage rule
Append 「なら（ば）」 to the noun, verb, or adjective
Example

  1. 友達＋なら = 友達なら
  2. 忙しい＋なら = 忙しいなら
  3. 忙しくない＋なら = 忙しくないなら
  4. 食べる＋なら = 食べるなら

Example

  1. 皆が行きたくないと言うなら、私も行かないよ。
    If everybody is saying (they) don’t want to go, I won’t go as well.
  2. アリスちゃんなら、もう家に帰ったよ。
    If (you’re) referring to Alice-chan, (she) went home already, you know.
  3. 昨日起きた話なら、田中さんからもう聞いたよ。
    If (you’re) referring to (the) story of (what) happened yesterday, (I) already heard from Tanaka-san.
  4. 忙しくないなら、どうして会えないの？
    If (you’re) not busy, why can’t you meet (me)?

Natural consequence

The natural conditional is used by appending 「と」 for verbs and i-adjectives or 「だと」 for nouns and na-adjectives.

This conditional is used to describe things that happen as a natural consequence with very high certainty ie, “If you do X, Y will certainly happen.” It can also be translated as “when” in addition to “if”.

Natural conditional usage rule
Append 「と」 to the noun, verb, or adjective
Example

  • For nouns/na-adjectives: Append 「だと」
    Example

    1. 友達＋だと = 友達だと
    2. 静か＋だと = 静かだと
  • For verbs/i-adjectives and negatives ending in 「ない」: Append 「と」
    Example

    1. する＋と = すると
    2. しない＋と = しないと
    3. 忙しい＋と = 忙しいと

Example

  1. 今から行かないと、電車に間に合わないよ。
    If (we) don’t go now starting now, (we) won’t make the train.
  2. 彼は暇だといつもゲームをしているの。
    If he’s free, (he) always plays game(s).
  3. そんなにたくさん食べると絶対太るよ。
    If (you) eat that much, (you’ll) get fat for sure.

Examples of different scenarios

It’s not often obvious nor easy to explain when you would use one type of conditional over another. The best way to master conditionals is by learning from many examples over time. To help you get started, below are a few examples to illustrate some scenarios where some conditionals are more appropriate then others. However, keep in mind, that no version is necessarily incorrect as it can depend on the context and the message the speaker is trying to convey.

学生 – student

  1. 学生であれば、学生割引が使えるよ。
    If (you) are (a) student, (you) can use student discount.
    (Generic conditional, no assumption whether you a student)
  2. ここの学生だったら、またすぐ会えるのにな。
    If only (he/she) was (a) student of here, (I) would be able to meet again soon.
    (Same as generic conditional but used for the past tense)
  3. 大学生なら、勉強をもっとすると思ったけど、全然していないよ。
    If (he/she) is a student, (I) thought (he/she) would study more but (he/she) doesn’t at all.
    (He/she is a student, ie “since he is a student…”)
  4. 学生だと、ここのラーメンは４００円だよ。
    If (you) are (a) student, ramen here is 400 yen.
    (Stating a fact)

忙しい – busy

  1. 忙しくなければ、映画を見に行こう。
    If (you’re) not busy, let’s go see (a) movie.
    (Generic conditional with no assumption of whether you’re busy or not)
  2. そんなに忙しかったら、どうして昼寝をしたの？
    If (you’re) that busy, why (did you) take a nap?
    (Same as generic conditional but used for the past tense)
  3. そんなに忙しいなら、話は明日にしましょう。
    If (you’re) that busy, let’s talk tomorrow.
    (It’s known that the person is busy ie “given that you’re busy…”)
  4. 仕事で忙しくなるといつもジャンクフードを食べたくなる。
    If (I) become busy with work, (I) always want to eat junk food.
    (Predetermined outcome, ie “when busy…”)

分かる – understand

  1. 方程式が分かれば、試験は簡単だよ。
    If (you) understand (the) formula, (the) test is simple.
    (Generic conditional that can be applied to anybody)
  2. 時間と場所が分かったら、皆にメールを送るよ。
    If (I) know the time and place, (I’ll) send email to everybody.
    (Used to express what happens after, ie “once (I) know…”)
  3. 私の気持ちが分からないなら、もう話す必要がないの。
    If (you) don’t understand my feeling(s), there is no need to talk anymore.
    (The person doesn’t seem to understand, ie “since you don’t understand…”)
  4. 電話番号が分からないと連絡が出来ないでしょう？
    If (you) don’t know (the) phone number, (you) can’t contact (him/her/them), right?
    (Expressing almost 100% certainty)
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