Translation guide
The English word "guess" covers a range of situations from casual speculation to formal conjecture. In Japanese, the best expression depends on whether you are making a rough estimate, a logical inference, or a random guess, and also on the level of certainty and formality.
To express a guess or hunch in everyday conversation, often with low certainty.
I guess he won't come.
A very casual sentence-ending particle used when wondering or guessing, often to oneself. Common in informal speech.
A plain form used for conjecture, similar to "probably" or "I guess". Often used in masculine speech or writing.
彼はもう帰っただろう。
I guess he's already gone home.
To express a guess based on evidence or reasoning, often with moderate to high certainty.
Indicates a strong expectation based on logic or information. "It should be..." or "I'm pretty sure..."
彼はもう着いているはずだ。
He should have arrived by now. / I'm pretty sure he's arrived.
鍵はここにあるはずだ。
The key should be here.
Expresses a strong conviction or guess, "must be" or "no doubt". Slightly more formal/literary.
あれは彼に違いない。
That must be him.
Used when making a guess based on sensory evidence or observation. "It seems like..."
誰か来たようだ。
It seems like someone has come.
To guess a number, amount, or time without precise calculation.
A noun meaning "guess" or "conjecture". Often used with する to mean "to guess" in a slightly formal or analytical context.
それはただの推測です。
That's just a guess.
彼の年齢を推測する。
Guess his age.
Attached to a number to mean "about" or "approximately". Used for rough guesses.
30分くらいかかると思う。
I guess it'll take about 30 minutes.
To make a guess in a guessing game, test, or when trying to identify something.
To guess correctly, to hit upon the answer. Often used in games like "guess the number".
答えを当ててください。
Please guess the answer.
何歳か当ててみて。
Try to guess how old I am.
Deduction or reasoning, often used in mystery contexts. "To deduce" rather than a blind guess.
To express a guess in academic, professional, or formal settings.
Also used in formal contexts for conjecture or estimation.
専門家の推測によると…
According to experts' guesses...
Conjecture, speculation, often with a nuance of being groundless. Used in formal writing.
English speakers often use 'I guess' as a filler or to soften a statement. In Japanese, directly translating this as 「私は推測する」 sounds unnatural. Instead, use 「〜と思う」 or 「〜かな」 to convey the same tentative feeling.
多分そうだと思う。
I guess that's probably the case.
推測 (suisoku) is a reasoned guess or estimate, while 当てずっぽう (atezuppō) is a wild, random guess. Use 推測 when you have some basis, and 当てずっぽう when you are just guessing blindly.
A wild guess, a shot in the dark. Casual and often used when the guess is random.
当てずっぽうで答えた。
I answered with a wild guess.
Guess who the culprit is. (Deduce)
それは単なる憶測だ。
That's mere speculation.