A 3LDK apartment in Japan is typically 70–90 m² (21–27 坪 / 평).
From a Japanese listing
Tatami size varies by region — the same “6畳” can differ by 15%+. Listings legally must also show ㎡.
3LDK
🏠 Family-sized apartment or a small house footprint.
㎡ is the legal size. 畳/坪 are traditional — always cross-check the ㎡ figure.