Assuming scenarios with 'としたら' and 'とすれば'
としたら to explore hypothetical possibilities and とすれば for logical assumptions in more formal contexts.
Grammar Rule in 30 Seconds
Use 'としたら' and 'とすれば' to set up a hypothetical scenario and explore its logical outcome.
- Use 'としたら' for casual, everyday hypothetical situations: {明日|あした}雨が降るとしたら、どうしますか？
- Use 'とすれば' for more formal, logical, or theoretical deductions: この計画が成功するとすれば、大きな利益が出る。
- Both follow the plain form of verbs, i-adjectives, na-adjectives, and nouns.
Overview
At the B2 level, moving beyond simple conditionals is essential for nuanced expression. The grammar patterns としたら (to shitara) and とすれば (to sureba) are sophisticated tools for this, allowing you to establish a hypothetical or assumed premise for the sake of argument, planning, or speculation. Unlike conditionals like 〜たら or 〜と, which often deal with likely or factual events, these patterns create a clear separation from reality.
They invite your listener to enter a mental sandbox and explore the consequences of a condition, without committing to its truth.
Think of them as the Japanese equivalent of saying, "Supposing that..." or "If we assume that...". While both serve this core function, they carry distinct nuances. としたら is the more common, versatile, and conversational of the two, used for a wide range of "what if" scenarios, from the imaginative to the practical.
とすれば is more formal, analytical, and logical, typically used when setting up a premise for a structured argument or a serious deduction. Mastering this distinction is key to sounding both fluent and precise.
How This Grammar Works
と (to), the verb する (suru), and a conditional ending (〜たら or 〜ば). Understanding this foundation reveals why the grammar behaves as it does.- 1The Quotative Particle
と(to): In this pattern,とfunctions to package the entire preceding clause into a single conceptual unit. It works just like it does in〜と思う(to omou, "to think that...") or〜と言う(to iu, "to say that..."). The clause, for example雨が降る(ame ga furu, "it will rain"), is treated as a single idea that becomes the object of the next verb.
- 1The Verb
する(suru): Here,するdoes not mean "to do." Instead, it means "to treat as," "to posit," or "to assume." When you combine the quoted clause withする, you get雨が降るとする(ame ga furu to suru), which literally means "to treat 'it will rain' as a given." This is the crucial step that establishes the premise as a mental construct rather than a fact.
- 1The Conditional Endings
〜たらvs.〜ば: The final piece determines the nuance.
としたら: This ending comes from the past tenseした(shita) plus the conditionalら(ra). The〜たらconditional is known for its versatility, often focusing on what happens after a specific condition is met. In this structure, it lends a more subjective, personal, and situational feel. It's perfect for a wide range of "What if this were to happen?" questions.もし彼が正しいとしたら、私たちが間違っていたことになる。(Moshi kare ga tadashii to shitara, watashitachi ga machigatteita koto ni naru.) – "If he's right, that would mean we were wrong." (A personal realization based on the assumption).とすれば: This ending uses the〜ばconditional form ofする(sureba). The〜ばconditional inherently emphasizes a logical or natural cause-and-effect relationship. Consequently,とすればcarries a more objective, analytical, and formal tone. It signals that what follows is a logical deduction or a necessary consequence of the premise.全ての証言が真実だとすれば、彼は無実です。(Subete no shōgen ga shinjitsu da to sureba, kare wa mujitsu desu.) – "If all the testimony is true, then he is innocent." (A formal, logical conclusion).
としたら poses a hypothetical situation to explore its potential outcomes, while とすれば establishes a formal premise to derive a logical conclusion.Formation Pattern
としたら or とすれば to the plain form (dictionary, negative, past, etc.) of verbs and i-adjectives. For nouns and na-adjectives, you must add the copula だ (da) or である (de aru).
としたら Example | とすれば Example |
行くとしたら (iku to shitara - If I were to go) | 行くとすれば (iku to sureba - If one goes) |
来なかったとしたら (konakatta to shitara - If he hadn't come) | 来なかったとすれば (konakatta to sureba - If he hadn't come) |
高いとしたら (takai to shitara - If it's expensive) | 高いとすれば (takai to sureba - If it is expensive) |
良くないとしたら (yokunai to shitara - If it's not good) | 良くないとすれば (yokunai to sureba - If it is not good) |
だ / である | 静かだとしたら (shizuka da to shitara - If it's quiet) | 静かだとすれば (shizuka da to sureba - If it is quiet) |
だ / である | 学生だとしたら (gakusei da to shitara - If he's a student) | 学生だとすれば (gakusei da to sureba - If he is a student) |
だ (da)
だ is not optional; it's grammatically essential. The quotative particle と needs to quote a complete predicate (a statement). A noun like 学生 or a na-adjective stem like 静か is not a full predicate. Adding だ turns it into a statement (学生だ - "is a student"), which can then be properly quoted. Forgetting だ is one of the most common errors learners make. In very formal writing, である (de aru) can be used instead of だ.
When To Use It
- 1Pure Hypotheticals & Counterfactuals: This is the classic use case for imagining things that are impossible, contrary to fact, or highly unlikely.
としたらis especially common here.
もし人生をやり直せるとしたら、今度は宇宙飛行士になりたい。(Moshi jinsei o yarinaoseru to shitara, kondo wa uchūhikōshi ni naritai.) - "If I could redo my life, I'd want to be an astronaut next time."宝くじで一億円が当たったとしたら、まず世界一周旅行に行く。(Takarakuji de ichiokuen ga atatta to shitara, mazu sekai isshū ryokō ni iku.) - "Supposing I won 100 million yen in the lottery, I'd first go on a trip around the world."
- 1Strategic Planning and Considering Contingencies: In both professional and personal contexts, these patterns are used to game out scenarios and make plans.
とすればcan add a more formal, analytical weight.
明日のプレゼンに部長が来られないとしたら、誰が代わりに発表しますか？(Ashita no purezen ni buchō ga korarenai to shitara, dare ga kawari ni happyō shimasu ka?) - "If the department head can't make it to tomorrow's presentation, who will present instead?"新しいシステムを導入するとすれば、少なくとも三ヶ月の準備期間が必要だ。(Atarashii shisutemu o dōnyū suru to sureba, sukunakutomo sankagetsu no junbi kikan ga hitsuyō da.) - "If we are to introduce the new system, a preparation period of at least three months will be necessary."
- 1Logical Deduction and Argumentation: This is the primary domain of
とすれば. It allows you to establish a premise and then state the logical conclusion that must follow, making it invaluable in debates, analysis, and proofs.
彼のアリバイが正しいとすれば、犯行は不可能である。(Kare no aribai ga tadashii to sureba, hankō wa fukanō de aru.) - "If his alibi is correct, then the crime would have been impossible."
When Not To Use It
- 1For Factual or Highly Probable Conditions: When a condition is a known fact, a reliable plan, or a very likely event, using
としたら/とすればintroduces unnecessary doubt. Use〜たらfor sequences or〜とfor guaranteed results.
- Incorrect:
大学を卒業するとしたら、就職する。(Daigaku o sotsugyō suru to shitara, shūshoku suru.) - Correct:
大学を卒業したら、就職する。(Daigaku o sotsugyō shitara, shūshoku suru.) - "When I graduate from university, I will get a job."
- 1For General Truths and Natural Consequences: For scientific facts or things that always happen,
〜とis the standard choice.としたらwould oddly frame a universal truth as a mere assumption.
- Incorrect:
春が来るとすれば、桜が咲く。(Haru ga kuru to sureba, sakura ga saku.) - Correct:
春が来ると、桜が咲く。(Haru ga kuru to, sakura ga saku.) - "When spring comes, the cherry blossoms bloom."
- 1For Advice Based on Shared Information (Use
〜なら): When you give advice based on something your conversation partner just said,〜ならis the correct choice.〜ならaccepts their statement as the context, whereasとしたらwould sound like you're questioning its reality.
- Context: A friend says,
「日本へ行くんだ。」("I'm going to Japan.") - Incorrect:
* 日本へ行くとしたら、京都がおすすめだよ。 - Correct:
日本へ行くなら、京都がおすすめだよ。(Nihon e iku nara, Kyōto ga osusume da yo.) - "If you're going to Japan, I recommend Kyoto."
Common Mistakes
- 1Using
としたらfor a Simple Future Plan: The most frequent mistake is usingとしたらwhen〜たらis needed. Remember,としたらis for hypothesizing, not planning.
- Mistake:
明日、会社に行くとしたら、この資料を持っていきます。(This sounds like you're not sure if you're even going to work tomorrow.) - Correction:
明日、会社に行ったら、この資料を持っていきます。(Ashita, kaisha ni ittara, kono shiryō o motte ikimasu.) - "When I go to the office tomorrow, I'll take these documents."
- 1Omitting
だwith Nouns and Na-adjectives: As mentioned in the formation section, this is a critical grammatical error. The particleとcannot directly follow a noun or na-adjective stem in this pattern.
- Mistake:
*あの建物が美術館としたら、入ってみよう。 - Correction:
あの建物が美術館だとしたら、入ってみよう。(Ano tatemono ga bijutsukan da to shitara, haitte miyō.) - "If that building is an art museum, let's go in."
- 1Using
とすればin a Casual Conversation: While grammatically correct, usingとすればwhen chatting with friends can sound stiff, overly formal, or even pretentious. Stick toとしたらfor everyday speculation.
- Unnatural (in casual chat):
もし来週のパーティーに行けるとすれば、何を着ていく？(Sounds like a logical problem.) - Natural:
もし来週のパーティーに行けるとしたら、何を着ていく？(Moshi raishū no pātī ni ikeru to shitara, nani o kite iku?) - "If you can go to the party next week, what will you wear?"
Real Conversations
Here’s how these patterns appear in natural, modern Japanese communication.
Planning with a Friend via Text Message (としたら):
- A: 週末、天気どうかな？ (Shūmatsu, tenki dō ka na?) - "How's the weather looking for the weekend?"
- B: んー、もし雨じゃないとしたら、山登りでもしない？ (N, moshi ame janai to shitara, yamanobori demo shinai?) - "Hmm, if it's not raining, wanna go hiking or something?"
Formal Business Email (とすれば):
- 貴社のご提案を受け入れるとすれば、契約条件について再交渉が必要となります。 (Kisha no goteian o ukeireru to sureba, keiyaku jōken ni tsuite saikōshō ga hitsuyō to narimasu.) - "If we are to accept your company's proposal, it will be necessary to renegotiate the contract terms."
Discussing a Character's Motives in an Anime (としたら):
- あの時点で彼が真実を知っていたとしたら、その後の行動の意味が全く変わってくるよね。 (Ano jiten de kare ga shinjitsu o shitte ita to shitara, sono go no kōdō no imi ga mattaku kawatte kuru yo ne.) - "If he knew the truth at that point, the meaning of all his later actions completely changes, doesn't it?"
Politely Challenging an Idea in a Meeting (とすれば):
- その分析が正しいとすれば、なぜAという結果が出なかったのか、説明が難しくなります。 (Sono bunseki ga tadashii to sureba, naze A toiu kekka ga denakatta no ka, setsumei ga muzukashiku narimasu.) - "Assuming that analysis is correct, it becomes difficult to explain why result 'A' did not occur."
Progressive Practice
Build your mastery of these forms with targeted exercises.
Step 1: Basic Formation
Convert the following words into the としたら form. Remember the rule for nouns/na-adjectives.
食べる (taberu) -> 食べるとしたら
高い (takai) -> 高いとしたら
簡単 (kantan) -> 簡単だとしたら
医者 (isha) -> 医者だとしたら
買わなかった (kawanakatta) -> 買わなかったとしたら
Step 2: Simple Sentence Construction
Complete the sentences with a logical or imaginative consequence.
もし透明人間になれたとしたら、＿＿＿＿。 (Moshi tōmei ningen ni nareta to shitara, ____.)
このプロジェクトが失敗したとすれば、＿＿＿＿。 (Kono purojekuto ga shippai shita to sureba, ____.)
Step 3: Choosing the Right Nuance
For each situation, choose between としたら and とすれば and briefly explain why.
(In a formal report) "If we assume the market grows by 5%..." -> とすれば is better due to the formal, analytical context.
(With a friend) "What if we had a dog? What should we name it?" -> としたら is better for a casual, imaginative hypothetical.
Step 4: Creating Your Own Scenarios
Write a short paragraph (2-3 sentences) for one of the following prompts, using としたら or とすれば at least once.
Imagine you receive a large inheritance. What is the first thing you do?
You are a detective. A key piece of evidence is proven to be fake. What are the implications?
Quick FAQ
としたら and とすれば?としたら is for general, often personal, "what if" speculation (more conversational), while とすれば is for formal, logical deduction based on a premise (more analytical).もし (moshi) with them?もし is frequently used with both としたら and とすれば to add extra emphasis to the hypothetical nature of the condition, like saying "If, by some chance..."としたら and とすれば compare to 〜とすると (~to suru to)?〜とすると is a very close cousin of とすれば and is often interchangeable. Both are used for logical deduction. Some speakers feel とすると points to a more direct or immediate consequence, almost like a calculation (A=Bとすると...), while とすれば is slightly broader, used for setting up a premise for a larger argument.〜した, 〜だった) before としたら/とすれば creates a counterfactual statement about the past—imagining a past that was different from reality. Example: もしあの時、正直に話していたとしたら... (Moshi ano toki, shōjiki ni hanashite ita to shitara... - "If I had spoken honestly at that time...").Formation Table
| Type | Form | Example |
|---|---|---|
|
Verb
|
Plain Form + としたら
|
行くとしたら
|
|
i-Adj
|
Plain Form + としたら
|
忙しいとしたら
|
|
na-Adj
|
Stem + だ + としたら
|
静かだとしたら
|
|
Noun
|
Noun + だ + としたら
|
休みだとしたら
|
|
Verb
|
Plain Form + とすれば
|
行くとすれば
|
|
i-Adj
|
Plain Form + とすれば
|
忙しいとすれば
|
|
na-Adj
|
Stem + だ + とすれば
|
静かだとすれば
|
|
Noun
|
Noun + だ + とすれば
|
休みだとすれば
|
Meanings
These structures are used to establish a hypothetical premise (a 'what if' scenario) to discuss a potential result or conclusion.
Hypothetical Premise
Setting a condition that is not currently true but is being considered for the sake of argument.
“もし君が私の立場だとしたら、どうする？”
“もし彼が来るとすれば、連絡があるはずだ。”
Reference Table
| Form | Structure | Example |
|---|---|---|
|
Affirmative
|
Plain + としたら
|
行くとしたら
|
|
Negative
|
Negative Plain + としたら
|
行かないとしたら
|
|
Past
|
Past Plain + としたら
|
行ったとしたら
|
|
Affirmative
|
Plain + とすれば
|
行くとすれば
|
|
Negative
|
Negative Plain + とすれば
|
行かないとすれば
|
|
Past
|
Past Plain + とすれば
|
行ったとすれば
|
Formality Spectrum
行くとしたら、どうしますか？ (Asking about future plans)
行くとしたら、どうする？ (Asking about future plans)
行くとしたら、どうするの？ (Asking about future plans)
行くとしたら、どうすんの？ (Asking about future plans)
Hypothetical Logic
Usage
- 仮定 Assumption
- 推論 Deduction
Form
- 普通形 Plain form
Examples by Level
明日、休みだとしたら何をする？
If you were off tomorrow, what would you do?
もし日本に行くとしたら、どこがいい？
If you were to go to Japan, where would be good?
この計画が成功するとすれば、何が必要ですか？
If this plan were to succeed, what would be needed?
彼が来ないとしたら、会議はどうなりますか？
If he were not to come, what would happen to the meeting?
仮にこれが真実だとすれば、歴史は書き換えられるべきだ。
If this were to be true, history should be rewritten.
彼がその場にいたとすれば、なぜ何も言わなかったのだろうか。
If he were indeed there, why did he say nothing?
Easily Confused
Learners often use 'たら' for everything. 'たら' is for real conditions, 'としたら' is for hypothetical.
They are very similar, but 'とすれば' is more logical/deductive.
Both are conditionals. 'ば' is a general conditional, 'としたら' is specific to hypothetical premises.
Common Mistakes
休みとしたら
休みだとしたら
行くとしたら
行くとしたら
雨だとしたら
雨だとしたら
静かとしたら
静かだとしたら
食べるとしたら
食べるとしたら
忙しいとしたら
忙しいとしたら
学生としたら
学生だとしたら
来るとしたら
来るとしたら
高いとしたら
高いとしたら
きれいとしたら
きれいだとしたら
真実としたら
真実だとしたら
可能としたら
可能だとしたら
行くとしたら
行くとしたら
来るとしたら
来るとしたら
Sentence Patterns
もし___だとしたら、どうしますか？
もし___するとしたら、何が必要ですか？
そうだとすれば、___。
もし彼が___としたら、驚きます。
Real World Usage
弊社に採用されるとしたら、どのような貢献ができますか？
明日暇だとしたら、映画行かない？
この理論が正しいとすれば、他の実験結果も説明がつく。
もし北海道に行くとしたら、いつがいいかな？
もし宝くじが当たるとしたら、みんなは何に使う？
競合他社が参入するとすれば、我々はどう対応すべきか。
Use 'Moshi'
Don't forget 'da'
Logical Deduction
Softening
Smart Tips
Use 'tosureba' instead of 'toshitara'.
Add 'moshi' to emphasize the hypothetical nature.
Always check for 'da'.
Use the past plain form.
Pronunciation
Intonation
The intonation rises slightly at the end of the conditional clause (toshitara/tosureba) to indicate it is a premise.
Hypothetical Rise
行くとしたら↗、...
Signals the start of a hypothetical condition.
Memorize It
Mnemonic
Think of 'Toshitara' as 'To-shi-tara' (Suppose-if).
Visual Association
Imagine a fork in the road where one path is 'Reality' and the other is a 'Cloudy Hypothetical' path. You are standing on the cloudy path.
Rhyme
If you want to guess, use 'toshitara' to express.
Story
Ken is planning a party. He thinks, 'If it rains, we move inside.' He uses '雨が降るとしたら' to set the condition. His friend replies, 'If that's the case, we need more chairs.' They use 'そうだとすれば' to agree on the logic.
Word Web
Challenge
Write 3 sentences about what you would do if you won the lottery today.
Cultural Notes
In Japanese business, 'とすれば' is often used to avoid direct confrontation when discussing problems by framing them as hypothetical.
Derived from the verb 'suru' (to do) and the conditional 'tara'/'ba'.
Conversation Starters
もし明日、宝くじが当たるとしたら何を買いますか？
もし日本に住むとしたら、どの都市がいいですか？
もしこのプロジェクトが失敗するとすれば、原因は何だと思いますか？
もしタイムマシンがあるとしたら、過去と未来、どちらに行きたいですか？
Journal Prompts
Common Mistakes
Test Yourself
もし明日が___としたら、何をしますか？
この計画が成功___、大きな利益が出るでしょう。
Find and fix the mistake:
もし彼が来ないとしたら、会議はどうする？
もし / 行く / としたら / どこ / に / 行きたい / ですか
もし静かだとしたら、勉強できる。
A: もし宝くじが当たるとしたら何を買う？ B: ___
忙しい + としたら = ?
Match each item on the left with its pair on the right:
Score: /8
Practice Exercises
8 exercisesもし明日が___としたら、何をしますか？
この計画が成功___、大きな利益が出るでしょう。
Find and fix the mistake:
もし彼が来ないとしたら、会議はどうする？
もし / 行く / としたら / どこ / に / 行きたい / ですか
もし静かだとしたら、勉強できる。
A: もし宝くじが当たるとしたら何を買う？ B: ___
忙しい + としたら = ?
Formal logical deduction
Score: /8
Practice Bank
10 exercises{留学|りゅうがく}(______)、イギリスに{行き|いき}たい。
[としたら] [だ] [本当] [ニュース] [が] [大変だ]
Supposing we look at the budget...
If I can't go tomorrow, I'll call you.
Match these pairs:
{暇|ひま}としたら、{遊ぼう|あそぼう}。
{彼|かれ}が{昨日|きのう}{来|こ}(______)としたら、{理由|りゆう}は何だろう？
If you are assigned to a different team...
If it were to snow tomorrow, I'd be happy.
[としたら] [を] [やり直す] [ゲーム] [もっと] [うまくできる]
Score: /10
FAQ (8)
Yes, you can use them with past plain forms to discuss hypothetical past scenarios, e.g., 'If I had gone, I would have seen him.'
No, it can be used for present or past hypothetical states.
'Toshitara' is for hypothetical conditions (if), while 'toshitemo' is for concessions (even if).
No, 'moshi' is optional but helps clarify the hypothetical nature.
Yes, just end the sentence with 'desu/masu'.
Because 'toshitara' attaches to the predicate form, and nouns need the copula 'da' to act as a predicate.
It can sound a bit stiff, but it's not 'wrong'. 'Toshitara' is generally better for friends.
No, use 'tara' or 'ba' for real conditions.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
Suponiendo que / Si fuera
Spanish requires verb conjugation for mood, while Japanese uses a fixed structure after the plain form.
Si + imparfait
French changes the verb tense, whereas Japanese keeps the plain form.
Angenommen, dass
German is a sentence-initial adverbial phrase, while Japanese is a clause-ending structure.
仮に～としたら
None.
بافتراض أن
Arabic is a formal prepositional phrase.
假设
Chinese is usually placed at the beginning of the sentence.
Learning Path
Prerequisites
Related Grammar Rules
Japanese 'To': The Inevitable If
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The More... The More (～ば～ほど)
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Useless Efforts: Even if... (~たところで)
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Turning Points: Once it becomes... (~ともなると)
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