そうだlooks like; I hear
Two endings share this spelling, and the word in front tells them apart. On a stem, おいしそうだ is "it looks delicious": you go by the look of it. On a whole plain form, おいしいそうだ is "I hear it's delicious": someone told you.
looks like
The sky has suddenly grown dark. It looks like it is going to rain.
I hear
According to the weather forecast, it will rain tomorrow.
Looks like
降ります → 降りそうだ ／ おいしい → おいしそうだ ／ 元気な → 元気そうだ
A verb loses ます, an い-adjective loses い, a な-adjective loses な. Two are irregular: いい → よさそうだ, ない → なさそうだ. A noun can't come straight before it.
I hear
降るそうだ ／ おいしいそうだ ／ 元気だそうだ ／ 雨だそうだ
The plain form, whole. A な-adjective or a noun keeps its だ. Polite for both: そうです.
Which one is it?
This ramen looks delicious.
おいしい has lost its い. You are looking at the bowl.
I hear this ramen is delicious.
おいしい is whole. A friend told you.
I hear Yamada is well.
With だ. You have had news of her.
After a past form it is always "I hear": 降ったそうです, "I hear it rained".
How do you know?
Japanese picks the ending by how you know: from the look of it, from signs, or from what you were told.
The sky is dark. No rain yet.
The look of it: stem + そうだ.
It looks like it's going to rain.
The road is wet. You figure it out.
Signs: plain form + ようだ, or みたいだ in conversation.
It seems it rained.
The forecast said so. You pass it on.
Told: plain form + そうだ.
I hear it's going to rain.
You heard it somewhere. You aren't vouching for it.
Told, and kept at a distance: plain form + らしい.
Apparently it's going to rain.
Looks like
With an adjective, it is your impression before you have checked: you haven't tasted it, lifted it or asked the price. It is also the normal way to talk about other people's feelings, which you only see from outside: うれしそう, 眠そう, 痛そう.
おいしそうlooks delicious
Steam is rising from this soup, and it looks delicious.
お元気そうlooking well
It's been a long time. You're looking well.
楽しそうlooks fun
I watched footage of the new game. It looks like a lot of fun.
よさそうlooks good
This place looks good. Let's go in.
With a verb: about to, or likely to
The box at the edge of the shelf is tilting and looks ready to fall at any moment.
Sorry, it looks like I'll be about five minutes late.
I'm so happy I could cry.
It looks like I can make it tomorrow.
About yourself, it is for what you don't decide: being late, crying, whether you can make it.
そうになった is "nearly did": it didn't happen.
I nearly fell on the stairs.
I was so happy I nearly cried.
そうな and そうに
This そうだ changes like a な-adjective: そうな before a noun, そうに before a verb. The "I hear" one has neither.
Delicious-looking bread is lined up in front of the shop.
The two of them were chatting, and looked like they were having a good time.
なさそう: it doesn't look…
ない becomes なさそう, by itself and at the end of a negative adjective: 難しくない → 難しくなさそう.
The equation is short, so this problem doesn't look very difficult.
It doesn't look like there will be time today.
A verb goes another way: 降りそうにない or 降りそうもない, "it doesn't look like it will rain".
Three catches
Not said: この
(This flower looks pretty.)
You can see that it is pretty, so there is nothing to guess: きれいですね.
Not said: あの
(That person looks like a student.)
A noun takes みたいだ or のようだ: 学生みたいです.
I saw an injured cat and felt sorry for it.
かわいそう is a word of its own, "pitiful". It doesn't mean "looks cute"; that is plain かわいい.
I hear
You pass on what someone told you or what you read, as you got it. によると or の話では names where it came from.
According to Tanaka, the shop by the station will close next month.
I hear that the manager of the new shop is Yamada.
Past and negative go inside what you heard, which stays in the plain form even in polite talk. そうです itself stays as it is.
I heard from my mother that my grandfather left the hospital yesterday.
English says "I heard", but the past goes on 退院した, not on そうです.
The teacher says next week's test won't be difficult.
I hear you…
I hear you're moving to Kyoto.
With ね, to the person the news is about.
With friends
I hear Yamada will arrive around seven.
To a colleague, politely.
I hear Yamada's arriving around seven.
To a friend.
Among friends the news mostly comes with らしい or んだって. そうです is at home in polite talk and in writing.
Close neighbours
ようだN4
Worked out from signs. For what has already happened it is this one: the "looks" そうだ can't follow a past form.
The road is still wet. It seems that it rained last night.
みたいだN4
ようだ as people say it in conversation. It goes straight after a noun.
That person seems to be a student.
らしいN4
Also what you were told, but kept at a distance: "apparently".
Apparently, this shop is closed on Mondays.
んだってN3
How friends pass on what someone said.
Yuki said that a movie theater is going to open behind the station.
The negative for a verb: "it doesn't look like it will".
There isn't a cloud in the sky, so it doesn't look like it will rain today.
に見えるN4
How something looks to the eye, true or not: bigger, younger, like a ship.
My mother looks younger than she is.
Check yourself
1What does this mean?
あの
Choose an answer to see why.
2Which one fits?
犬が
Choose an answer to see why.
3"I hear it will rain tomorrow."
明日は
Choose an answer to see why.
More detail
In conversation
A verb's negative also takes そう directly: 降らなそう, or 降らなさそう. And "doesn't look tasty" is often おいしそうじゃない.
Doesn't look like it'll rain today, does it?
帰りたそう: looks as if they want to
たい loses its い like any い-adjective.
The children look as if they want to go home soon.
How it looked
They looked delicious, so I bought two.
More sentences
This cake has plenty of cream and looks sweet.
It faces south and has big windows, so this room looks like it gets plenty of sun.
You can hear the laughter from outside. The hall doesn't sound quiet.
According to my friend, this movie is very interesting.
The news says that the airport has not reopened yet.
According to the article, that town used to be very quiet.
According to the email from the school, tomorrow's class will be online.