Japanese Conditionals: Tara vs Ba vs To vs Nara

For my first year of Japanese, I used たら for every single "if." It mostly worked, which is exactly why it was dangerous. Then one day I told a coworker "時間じかんがあるとメールしてください," trying to say "if you have time, please email me." He tilted his head. What I had actually said was closer to "whenever time exists, email happens automatically," and then I bolted a polite request onto it. It sounded like a broken vending machine.

That was the day I learned the hard truth about Japanese conditionals. English has one word, "if," and Japanese has four that all get translated as "if" in your textbook. たら (tara), ば (ba), と (to), and なら (nara) are not interchangeable. Each one carries a different assumption about how sure the result is and what kind of result is even allowed.

This is one of the biggest walls between N5 grammar and sounding genuinely intermediate, so let's take the four of them apart one at a time.

Short answer: if you only remember one, use たら (tara). It is the most flexible "if/when," and it lets the second half of the sentence be a request, a command, or your own plan. Use と (to) only for automatic, always-true results, never with a request. Use ば (ba) for hypothetical, condition-focused "if." Use なら (nara) when you are reacting to something the other person just brought up.

Table of Contents

• The One-Line Difference
• と (to): Automatic and Always True
• ば (ba): Hypothetical, Focused on the Condition
• たら (tara): The Flexible One
• なら (nara): Reacting to Context
• Quick Comparison Table
• Your Cheat Sheet
• Try It Yourself

The One-Line Difference

Before the details, here is the mental model that finally fixed this for me:

• と = a switch. Do A, and B always happens. No opinions, no requests.
• ば = a hypothetical. If A were true, B. The spotlight is on the condition.
• たら = a timeline. After/when A happens, then B. B can be anything, including "please do it."
• なら = a reaction. If it's the case that A, which you just mentioned, then here's B.

Everything below is just these four lines with real examples.

と (to): Automatic and Always True

Use と when A always leads to B: natural laws, machines, directions, math. There is no choice and no uncertainty involved.

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.
If you press this button, the door opens.

春はるになると、桜さくらが咲さきます。
Haru ni naru to, sakura ga sakimasu.
When spring comes, the cherry blossoms bloom.

Now the one rule about と that is genuinely strict, not a soft tendency: the second half cannot be a request, command, invitation, or your own intention. That is the exact mistake from my vending-machine story. A machine-like automatic result cannot end in "please."

✗ 時間じかんがあると、メールしてください。
✓ 時間じかんがあったら、メールしてください。

If you catch yourself putting てください, てはいけません, or ましょう after a condition, と is the wrong tool. Where と shines instead is directions, because arriving somewhere really is automatic:

この道みちをまっすぐ行いくと、駅えきがあります。
Kono michi o massugu iku to, eki ga arimasu.
If you go straight down this road, there's the station.

ば (ba): Hypothetical, Focused on the Condition

Use ば for a hypothetical "if" where the condition itself is the point: "if this one thing were true, the result follows." It feels a little more formal and shows up a lot in proverbs and general statements. Our ば-form guide covers exactly how to build it.

安やすければ、買かいます。
Yasukereba, kaimasu.
If it's cheap, I'll buy it.

ちりも積つもれば山やまとなる。
Chiri mo tsumoreba yama to naru.
Even dust, if it piles up, becomes a mountain. (Little things add up.)

One soft caution, and notice this is a tendency, not the hard wall that と has: when the condition is an action verb and both halves share a subject, ending ば with a command usually sounds off, and native speakers reach for たら instead.

✗ 図書館としょかんに行いけば、この本ほんを返かえしてください。
✓ 図書館としょかんに行いったら、この本ほんを返かえしてください。

ば is happiest with states and general truths (安やすければ, あれば, 見みれば). If you can use it like たら sometimes, sure, but when you want to ask someone to do something, たら is the safer bet.

たら (tara): The Flexible One

If you are unsure, たら is almost always safe. It means "when/after A happens, then B," and the second half can be a request, a command, an invitation, or your own plan. You build it from the plain past (た-form) plus ら, but do not let that fool you: たら is not about the past. It points to the moment after the condition is met, which is usually the future.

時間じかんがあったら、電話でんわしてください。
Jikan ga attara, denwa shite kudasai.
If you have time, please call me.

日本にほんに着ついたら、連絡れんらくします。
Nihon ni tsuitara, renraku shimasu.
When I arrive in Japan, I'll get in touch.

The one time たら really does lean past is when it reports a surprise discovery. Here it means "when," not "if":

家いえに帰かえったら、誰だれもいなかった。
Ie ni kaettara, dare mo inakatta.
When I got home, nobody was there.

This flexibility is why たら is the workhorse of everyday speech. The trick to sounding intermediate is knowing when not to reach for it, and that is where なら comes in.

なら (nara): Reacting to Context

なら is the one learners skip, and it is the one that makes you sound advanced. Use it when you are responding to something that was just said: "if it's the case that... then here's my take." It often carries advice or an opinion.

A: 京都きょうとに行いきたいです。 (I want to go to Kyoto.)
B: 京都きょうとに行いくなら、電車でんしゃが便利べんりですよ。
Kyouto ni iku nara, densha ga benri desu yo.
If you're going to Kyoto, the train is convenient.

Look at the timing: B's advice comes before the trip. That is the なら signature. The result can happen before the condition, because なら is about the topic ("as for going to Kyoto"), not the sequence of events. This is also the single most useful contrast to burn into memory, なら (before) versus たら (after):

京都きょうとに行いくなら、カメラを買かいます。 → Buy the camera before going (preparing).
京都きょうとに行いったら、カメラを買かいます。 → Buy the camera after arriving.

Mix these up and you get sentences that are physically impossible, like getting your visa after you have already flown to Japan:

✗ 日本にほんに行いったら、ビザを取とります。
✓ 日本にほんに行いくなら、ビザを取とります。

Quick Comparison Table

Your Cheat Sheet

When you are mid-sentence and stuck, run these quick checks in order:

1. Is the result a request, command, or your own plan? Then it cannot be と. Use たら, or なら if you're reacting to what someone said.
2. Is the result 100% automatic every single time? Use と.
3. Are you responding to something the other person just brought up? Use なら.
4. Still unsure? Use たら. It is rarely wrong.

Try It Yourself

Pick the natural conditional for each blank. The answers, with the reason, are right below.

1. 時間じかんがあっ＿＿＿、電話でんわしてください。
2. このボタンを押おす＿＿＿、ドアが開あきます。
3. 京都きょうとに行いく＿＿＿、電車でんしゃが便利べんりですよ。

Answers: (1) たら, because the result is a request, so と is out. (2) と, an automatic machine result. (3) なら, because you're reacting to someone's stated plan and giving advice.

Not sure why a sentence uses one form over another? Paste it into our Japanese Sentence Analyzer and it breaks the verb form and particles down for you. And if you want this kind of pattern drilled in real conversations, Benkyō: Speak & Learn Japanese turns grammar like this into a few minutes of daily practice.

Conditionals are the point where Japanese stops being a word-swap of English and starts being its own logic. You are no longer asking "how do I say if," you are asking "how sure am I, and what am I allowed to do with the result." That shift is exactly what intermediate study is about. Reinforce it next with the た-form, ば-form, and と-conditional guides.