そうだLooks/seems (appearance)
そうだ expresses an impression based on what you can currently see, hear, or otherwise notice. With an adjective it means that something looks a certain way; with a verb it predicts that an event appears likely or close to happening.
What the speaker is judging
The speaker is not stating the property or event as a confirmed fact. Instead, current signs create an impression: steam may make food look delicious, dark clouds may suggest rain, or an unstable object may appear ready to fall.
Impressions and predictions
Adjectives describe the impression something gives. Verbs describe an event that current conditions make likely or imminent.
湯気が出ていて、このスープはおいしそうです。
Steam is rising from this soup, and it looks delicious.
Analyze新しいゲームの映像を見ました。とても楽しそうです。
I watched footage of the new game. It looks like a lot of fun.
Analyze空が急に暗くなりました。雨が降りそうです。
The sky has suddenly grown dark. It looks like it is going to rain.
Analyze棚の端にある箱が傾いていて、今にも落ちそうです。
The box at the edge of the shelf is tilting and looks ready to fall at any moment.
AnalyzeChanging the ending
At the end of a sentence, use そうだ or polite そうです. Before a noun, change the ending to そうな; before a verb, change it to そうに.
Before nouns and verbs
Appearance versus reported information
Appearance そうだ follows a verb stem and gives a prediction from current signs. The identically written hearsay ending follows the verb's plain form and reports information received from someone or somewhere else.
黒い雲が出てきました。雨が降りそうです。
Dark clouds have appeared. It looks like it is going to rain.
AnalyzeThe prediction comes from visible signs.
天気予報では、午後から雨が降るそうです。
According to the weather forecast, I hear it will rain from the afternoon.
AnalyzeThis is the neighboring hearsay use: the information comes from a report.
More examples
南向きで窓が大きいので、この部屋は日当たりがよさそうです。
Because it faces south and has large windows, this room looks as though it gets good sunlight.
AnalyzeUse よさそう, not いいそう, for this appearance meaning.
式が短いので、この問題はあまり難しくなさそうです。
The equation is short, so this problem does not look very difficult.
Analyze外まで笑い声が聞こえます。会場は静かではなさそうです。
Laughter can be heard outside. The venue does not seem quiet.
Analyze雲一つないので、今日は雨が降りそうもありません。
There is not a cloud in the sky, so it does not look as though it will rain today.
Analyzeクリームがたっぷりで、このケーキは甘そうです。
This cake has plenty of cream and looks sweet.
Analyze試作品が順調に動いているので、この計画はうまくいきそうです。
The prototype is working smoothly, so this plan looks likely to succeed.
Analyze