戸 draws just one leaf of 門 (gate). If 門 is a double-leaf gate that opens both ways, 戸 is a single-leaf door — the small door into a room. From there grew "household, family." A single-leaf door came to stand for one home.

The form splits three ways: traditional (ko/en/es) is 戶, Japanese shinjitai (ja) is 戸, Chinese simplified (zh) is 户 — the top stroke differs by mode (dot, sweep, or horizontal).

Korean hanja-sound "ho": 戶口 (hogu, household and members), 戶籍 (hojeok, family register), 窓戶 (changho, windows and doors), 門戶 (munho, a gateway), 家家戶戶 (gagahoho, every household). 戶 is the household unit of Korean administration.

Mandarin: hù, 4th tone. 户 (hù, household), 户口 (hùkǒu, household registration), 门户 (ménhù, gateway / portal), 账户 (zhànghù, account), 用户 (yònghù, user). China's 户口 (hùkǒu) residence-registration system is central to social policy.

Japanese: on-reading コ (ko), kun と (to). 戸 (to, door), 戸口 (kokō, households), 江戸 (Edo, old Tokyo), 雨戸 (amado, storm shutter), 井戸 (ido, a well). This is the 戸 of the Edo period (1603–1868).

Memory aid: one leaf of a gate (門) — a single-leaf door standing for one home.