Pyeong

A pyeong (Hangul: 평, Japanese Romaji: tsubo; Chinese: 坪; pinyin: píng; Pe̍h-ōe-jī: phêng), is an areal unit used to measure the size of rooms or buildings in Korea, Japan, and Taiwan equal to 36 shaku², where one shaku (尺, Japanese foot; Hangul: 자; RR: ja) is  ¹⁰⁄₃₃ m. Thus, one pyeong is approximately  ⁴⁰⁰⁄₁₂₁  square metres (3.3058 m², 3.954 sq yd or 35.586 sq ft). This unit is derived from Chinese Zhou Dynasty '步' unit.

In Japan, the size of a room is often measured by the number of tatami mats (-畳 -jō). Alternatively, house floor area is measured in terms of tsubo, where one tsubo is the area of two tatami mats (a square). One tsubo is almost the area of 2 blocks of the standard tatami put together into a square since the Edo Period (江戸時代).

Although Japanese rule in Taiwan ended in 1945 and Taiwan is now fully metricated, the ping is still commonly used.

In South Korea, a new law enacted as of July 1, 2007 replaced the use of pyeong in official documents with the square metre. A studio apartment will generally be around 8 to 12 pyeong, a house somewhere around 25 or more, and the smallest of rooms, consisting of only a bed and a bit of floor space for students, will be as little as 1.5 pyeong.