〜とすれば / 〜としたら / 〜とすると: 'Supposing That'
What it means
These three patterns take a supposition and draw a conclusion from it. The structure is always: [assume this] → [then this follows].
Think of them as "supposing…", "if we assume…", or "if that's the case…". The speaker isn't necessarily saying the premise is true — they're 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.
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.
How to form it
All three attach to the plain (dictionary) form of verbs and い-adjectives. With nouns and な-adjectives, you insert だ first.
| 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 — which is why all three feel like conditionals built on the same idea.
The subtle differences
All three are very close and often interchangeable, but there are tendencies:
- 〜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.
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.
"From the standpoint of…"
When attached to a noun, 〜としたら／〜とすれば can also mean "from the standpoint of" or "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…".
とすれば vs なら
Both can translate as "if," so learners mix them up. Compare them carefully:
- 〜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.
Common mistakes
- Using them for a real, decided plan. These assume a premise for argument's sake. For a concrete plan you've actually settled on, 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.
- Forgetting だ with nouns and な-adjectives. It's 本当だとすれば and 便利だとすると, never 本当とすれば.
- Treating とすると as a simple "if." とすると highlights a consequence that would follow ("that would mean…"). Don't use it where you just mean a neutral condition.
- Confusing them with なら's reactive feel. なら picks up something just mentioned; とすれば／としたら build a hypothesis you're choosing to entertain.
Quick recap
- 〜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).
Your turn
Choose the natural use of とすれば / としたら / とすると.
Start the 5-question drill →Take the full N3 〜とすれば drill →
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.