〜とすれば / 〜としたら / 〜とすると: 'Supposing That'
The kind of "if" it is
These three patterns take a supposition and draw a conclusion from it. The structure is always [assume this] → [then this follows]. Think "supposing…", "if we assume…", or "if that's the case…" — the speaker isn't claiming the premise is true, just entertaining it to see what would result.
宝くじが当たったとしたら、何を買う？
たからくじが あたったと したら、なにを かう？
Supposing you won the lottery, what would you buy?
A pure hypothesis — you haven't actually won.
The three variants split along the seam noted above — each keeps the flavour of the base conditional tucked inside it:
- 〜としたら is the most neutral and conversational — great for casual hypotheticals like 宝くじが当たったとしたら.
- 〜とすれば leans slightly more logical or written, common when reasoning carefully from a premise.
- 〜とすると often carries the sense of "that would mean…" — it emphasizes the consequence that automatically follows from the assumption.
Attached to a noun, 〜としたら／〜とすれば can also shade into "from the standpoint of" — "if you're in the position of":
親としたら、子どもの将来が心配だ。
おやと したら、こどもの しょうらいが しんぱいだ。
From a parent's standpoint, you worry about your child's future.
としたら after a noun = 'if you were / as a…'.
This grows naturally out of the core meaning: "supposing you are X, then…".
When it holds — and when it breaks
All three attach to the plain (dictionary) form of verbs and い-adjectives. With nouns and な-adjectives, insert だ first — that だ is the seam where the hidden する docks, so dropping it (本当とすれば ✗ for 本当だとすれば) is the single most common slip.
| Word type | Attach to | Example |
|---|---|---|
| Verb | plain form + とすれば／としたら／とすると | 行く → 行くとすれば |
| い-adjective | plain form + … | 安い → 安いとしたら |
| な-adjective | だ + … | 便利 → 便利だとすると |
| Noun | だ + … | 本当 → 本当だとすれば |
The verb 〜とする here literally means "to take it that…" / "to assume that…"; すれば is its ば-form, したら its たら-form, すると its と-form.
Where these patterns break is the settled plan. Because you assume a premise for argument's sake, they don't fit a concrete plan you've actually decided on — there, plain たら or なら is more natural: 帰ったら電話する ("I'll call when I get home"), not 帰るとすれば電話する. And keep とすると honest to its "that would mean…" job: don't reach for it where you only mean a neutral condition.
In real sentences
Reasoning forward from an assumed premise, letting the consequence fall out:
この情報が本当だとすれば、大変だ。
この じょうほうが ほんとうだと すれば、たいへんだ。
If we assume this information is true, that's serious.
Reasoning forward from an assumed premise.
ヤッタンが留学するとすると、お金がたくさん必要だ。
ヤッタンが りゅうがくすると すると、おかねが たくさん ひつようだ。
Supposing Yattan studies abroad, he'll need a lot of money.
とすると works through the consequences of the assumption.
When the assumption forces a particular outcome, とすると draws it out as "that would mean…":
モチが来ないとすると、二人で行くしかない。
モチが こないと すると、ふたりで いくしか ない。
If Mochi isn't coming, that means we'll just have to go, the two of us.
とすると = 'that would mean' — drawing out the inevitable result.
先生の話が正しいとすれば、試験の範囲が変わる。
せんせいの はなしが ただしいと すれば、しけんの はんいが かわる。
Assuming what the teacher said is correct, the exam scope changes.
Set against the other conditionals
Both these and なら can translate as "if," so learners mix them up:
- 〜とすれば／としたら = "supposing that [premise], then reasoning follows." You deliberately assume the premise to explore its consequences. It feels analytical.
- 〜なら = responds to information just raised, picking it up as the topic: "if (it's the case that)…, then [advice/reaction]." It's lighter and reacts to context rather than building an argument.
For example, 日本へ行くなら、京都がおすすめだ ("If you're going to Japan, I recommend Kyoto") reacts to your stated plan. By contrast, 日本へ行くとしたら、いくらかかるだろう ("Supposing one went to Japan, how much would it cost?") sets up a hypothesis and reasons from it. You can review なら and the broader conditional family — the た〜たら conditional and the と conditional — to see how とする borrows their shapes.
The short version
- 〜とすれば／としたら／とすると = "supposing that / if we assume" → then reason from it.
- They attach to the plain form; nouns and な-adjectives need だ first.
- としたら is neutral/casual, とすれば more logical, とすると often = "that would mean."
- After a noun they can mean "from the standpoint of."
- They assume a premise for argument's sake — not a real, settled plan (use なら or たら for that).
Practice it
Choose the natural use of とすれば / としたら / とすると.
＿＿＿に入れるのに最もよいものを選びなさい。
＿＿＿、大変なことになる。
Frequently asked questions
Are とすれば, としたら, and とすると interchangeable?
Mostly yes — all mean 'supposing that.' Tendencies: としたら is the most neutral and conversational, とすれば leans more logical or written, and とすると often emphasizes the consequence ('that would mean…').
How do they attach to nouns?
Insert だ first: 本当だとすれば ('if it's true'), 学生だとしたら ('supposing you're a student'). The same applies to な-adjectives: 便利だとすると.
What's the difference between とすれば and なら?
とすれば/としたら deliberately assume a premise to reason from it (analytical). なら reacts to information just raised and offers advice or a response. 行くなら… picks up your stated plan; 行くとすれば… entertains it as a hypothesis.
Can I use these for my actual plans?
Not naturally. They assume a premise for argument's sake. For a real, decided plan use たら or なら: 帰ったら電話する ('I'll call when I get home'), not 帰るとすれば電話する.
Where 〜とすれば / 〜としたら / 〜とすると fits
Shaky on this? Get these solid first
- Conditional 〜たら · N4 — 〜たら is Japanese's most flexible conditional: just add ら to the plain past. Learn the formation, the 'if/when' meaning, the discovery use, and how it beats ば/と for requests.
- Past Tense · N5 — The plain past た-form means 'did.' It follows the same sound changes as the て-form (just て→た, で→だ): 食べた, 行った, 飲んだ. Learn it by verb group.
Don't confuse it with
- Conditional 〜なら · N4 — 〜なら is the contextual 'if': it picks up a topic or premise — 日本に行くなら京都がいい. Learn the formation, how it differs from ば・たら・と, and why the main clause can come first.
- Conditional 〜と · N4 — The と conditional links A to an inevitable result B: 春になると、桜が咲く. Learn the plain-form formation, why B can't be a request, and how it differs from ば/たら/なら.
- Conditional 〜たら · N4 — 〜たら is Japanese's most flexible conditional: just add ら to the plain past. Learn the formation, the 'if/when' meaning, the discovery use, and how it beats ば/と for requests.
More N3 grammar to explore
Keep going with related patterns at the same level:
- 〜一方だ — 〜一方だ marks a one-way, ongoing change that keeps intensifying — 物価は上がる一方だ ('prices keep rising'). Learn the form, the change-verb rule, and how it differs from 一方で.
- 〜かけ / 〜かける — 〜かけ attaches to a verb stem to mean an action is started but unfinished: 食べかけのパン (half-eaten bread), 読みかけの本 (book I'm partway through), 死にかけた (nearly died).
- 〜うちに — 〜うちに means 'while a state lasts' — do something before it changes: 明るいうちに帰ろう. Learn 〜ないうちに ('before X happens'), 〜ているうちに, and うちに vs 間に.
- 〜ことだ — 〜ことだ gives direct, practical advice — 'the best thing is to' / 'you should.' Learn the formation, how it differs from べき and the nominalizer こと, and common mistakes.
- 〜まま — 〜まま means a state stays unchanged while something else happens: 電気をつけたまま寝た ('slept with the light on'). Learn た/ない/noun/adjective forms and そのまま.
- 〜ながら（も） — The concessive 〜ながら（も） means 'although / even though,' pointing out a contradiction between two facts about the same subject: 彼は忙しいながら、健康に気をつけない. Not to be confused with the 'while doing' ながら.