Japanese Conditionals Explained

Ever feel like every time you want to say "if" or "when" in Japanese, you're faced with a half-dozen choices? You're not alone. The subtle differences between ～たら (tara), ～ば (ba), ～なら (nara), ～と (to), and ～時とき (toki) are a common hurdle for learners.

Using the wrong one can make your sentences sound unnatural or, in some cases, change the meaning entirely. For example, some can be used for commands ("If you see him, tell him!") while others absolutely cannot.

This guide will clearly break down these five common phrases. We'll look at what each one really means, when to use it, and what restrictions to watch out for. By the end, you'll have a much clearer map for navigating these tricky but essential grammar points.

Key Differences at a Glance

Before we dive deep, here’s a high-level comparison. The first big split is between conditionals (if) and temporals (when). ～時とき (toki) is purely temporal, while the other four all carry some conditional "if" meaning.

The All-Rounder: ～たら (tara)

If you only remember one, make it ～たら. It's the most versatile and common conditional in spoken Japanese. It's formed by adding ～ら to the past tense (た form) of a verb or adjective.

The core meaning is "After X happens (or if X happens), then Y." It focuses on the completion of the first action or state.

Use Case 1: Conditional ("If")

Used for a specific, one-time condition and its result.

• お 金 かねがあったら、 旅行 りょこうに 行 いきます。
• Okane ga attara, ryokou ni ikimasu.
• If I have money, I will go on a trip.

Use Case 2: Temporal ("When")

Used when one action follows another in sequence.

• 家 いえに 着 ついたら、 電話 でんわしてください。
• Ie ni tsuitara, denwa shite kudasai.
• When you get home, please call.

The Hypothetical: ～ば (ba)

～ば is more formal and is used for hypothetical or logical conditions. It's formed by changing the final ～う sound of a verb to ～えば (e.g., 買かう kau → 買かえば kaeba) and ～い for adjectives to ～ければ (e.g., 安やすい yasui → 安やすければ yasukereba).

Think of it as "If X is true (as a general rule), then Y is the logical result."

• 安 やすければ、 買 かいます。
• Yasukereba, kaimasu.
• If it's cheap, I'll buy it. (A general rule for my shopping.)

• 春 はるになれば、 花 はなが 咲 さきます。
• Haru ni nareba, hana ga sakimasu.
• If it becomes spring, flowers bloom. (A logical, natural consequence.)

The Contextual "If": ～なら (nara)

～なら is the "contextual" conditional. It's used when you're making a statement or giving advice based on information you just heard or a topic that was just raised.

Think of it as "If that's the case..." or "Speaking of X..."

Example Scenario:

You: 「 来週 らいしゅう、 日本 にほんに 行 いきたいです。」 (Raishuu, Nihon ni ikitai desu.)
"I want to go to Japan next week."

Your Friend: 「 日本 にほんに 行 いくなら、 京都 きょうとがおすすめです。」 (Nihon ni iku nara, Kyoto ga osusume desu.)
"If you're going to Japan (since you mentioned it), I recommend Kyoto."

Your friend's advice is conditioned on the topic you brought up. Unlike ～たら, the action in the ～なら clause doesn't have to happen first. You can give advice about Kyoto before the person actually goes.

The Natural Consequence: ～と (to)

～と is the conditional of certainty. It's used when Y is a natural, habitual, or 100% certain result of X. It's like a scientific law or a machine's function.

It translates to "When X happens, Y always follows."

Use Case 1: Natural Law / Certainty

• 春 はるになると、 花 はなが 咲 さきます。
• Haru ni naru to, hana ga sakimasu.
• When spring comes, flowers bloom. (Always happens.)

Use Case 2: Habitual Action

• このボタンを 押 おすと、ドアが 開 あきます。
• Kono botan o osu to, doa ga akimasu.
• When you press this button, the door opens. (A reliable result.)

Like ～ば, ～とcannot be followed by commands, suggestions, or requests. It's a statement of fact, not a trigger for a personal action.

The Specific "When": ～時とき (toki)

Finally, ～時とき (toki). This one is simple: it is not a conditional "if." It is a purely temporal marker that means "when" or "at the time of."

The trickiest part of ～時とき is that the tense of the verb before it changes the meaning.

Example 1: Dictionary Form (Before)

• 日本 にほんへ行いく時とき、パスポートを 買 かいました。
• Nihon e iku toki, pasupooto o kaimashita.
• When I went to Japan, I bought a passport. (Meaning: I bought the passport before I left.)

Example 2: Past Tense (After/During)

• 日本 にほんへ行いった時とき、お 土産 みやげを 買 かいました。
• Nihon e itta toki, omiyage o kaimashita.
• When I went to Japan, I bought souvenirs. (Meaning: I bought the souvenirs after I arrived in Japan.)

Common Mistakes to Avoid

1. Using ～と or ～ば for Commands:

   Remember, only ～たら, ～なら, and ～時とき can naturally be followed by commands or requests.
   Incorrect:駅えきに着つくと、電話でんわしてください。
   Correct:駅えきに着ついたら、電話でんわしてください。

2. Confusing ～たら and ～時とき:

   ～たら implies a sequence ("after you arrive..."). ～時とき implies a point in time ("at the time of arriving...").
   着ついたら電話でんわして。 (Call me after you've arrived.)
   着つく時とき電話でんわして。 (Call me as you are arriving.)

3. Using ～なら for General Hypotheticals:

   ～なら is for contextual assumptions, not general "if" statements.
   Incorrect:明日あした晴はれるなら、ピクニックに行いきます。
   Correct:明日あした晴はれたら、ピクニックに行いきます。

Frequently Asked Questions

Can ～たら (tara) and ～ば (ba) be interchanged?

Sometimes, but they have different nuances. ～たら is better for specific, one-time events (especially with commands), while ～ば is better for general truths or logical, hypothetical conditions. For example, "If you press this, it works" (general) is better with ～ば. "If it rains, I'll stay home" (specific plan) is better with ～たら.

What's the simplest rule for these conditionals?

When in doubt, ～たら is often the safest and most versatile choice for "if" or "when" in daily, casual conversation. It can cover conditions, sequences of events, and be used with commands or suggestions.

Does ～時とき (toki) ever mean 'if'?

No.～時とき (toki) strictly means "when" or "at the time of." It is a temporal marker, not a conditional one. It doesn't carry the "if" (hypothetical) nuance that ～たら, ～ば, and ～なら do.