The Difference Between 暑い Vs 熱い Vs 厚い (Atsui) ｜Japanese Grammar (N5–N3)

(Alt Text: Joy sweating [暑い], touching hot tea [熱い], holding a thick book [厚い])

br> (Joy sweating [暑い], touching hot tea [熱い], holding a thick book [厚い])

“It’s hot today.” “This tea is hot.” “This book is thick.” In Japanese, all of these are pronounced 「あつい (Atsui)」! However, the Kanji is different for each one. Let’s master the three “Atsui” with Joy and Ken.

🗣 Conversation Scene

It is a summer day. Joy is studying at a cafe.

Joy

ふう、今日は暑（あつ）いですね。この辞書（じしょ）、厚（あつ）いから重（おも）いです…。 (Phew, it is “hot (weather)” today. This dictionary is “thick”, so it’s heavy…)

Ken

お疲れ様です。コーヒーを買ってきましたよ。まだ熱（あつ）いから気をつけてください。 (Good work. I bought you coffee. It’s still “hot (object)”, so be careful.)

💡 Explanation

Check the Kanji Radicals (Parts)!

1. 暑い (Weather / Climate)

Meaning: Hot (Atmosphere) Used for weather, room temperature, or air. Kanji Tip: It has the Sun (日) on top. The sun makes the weather hot.

暑い夏（なつ）。 (Hot summer.)
部屋（へや）が暑い。 (The room is hot.)

2. 熱い (Objects / Touch / Passion)

Meaning: Hot (To the touch) Used for food, drinks, body temperature (fever), or feelings (passion). Kanji Tip: It has Fire (灬) at the bottom. Fire makes things hot.

熱いコーヒー。 (Hot coffee.)
熱い気持ち。 (Passionate feelings / Hot heart.)

3. 厚い (Thickness)

Meaning: Thick Used for books, paper, coats, walls, or steaks. Opposite: Thin (薄い – Usui).

厚い本（ほん）。 (A thick book.)
厚いコート。 (A thick coat.)

📊 Comparison Table

Kanji	Target	Visual Cue
暑い	Weather, Air	☀️ Sun (Top)
熱い	Things, Touch, Fever	🔥 Fire (Bottom)
厚い	Dimension, Width	📚 Stacked items

🚧 Joy’s Mistake

(Joy touches a hot pot) ❌ Wrong: あちっ！この鍋（なべ）は暑いです！ (You used the “Weather” Kanji. The pot is not “Summer weather”.) ✅ Right: あちっ！この鍋は熱いです！ (Use the “Fire” Kanji for hot objects.)