What ken means
Ken names the space between two columns and serves as the unit for counting those spaces. In the structure field of the National Cultural Properties Database it is the basic measure of a building's size.
Counting bays is the primary use. The offering hall at Kasuga Shrine in Oita Prefecture, built in 1905, is recorded as one bay by one; the main hall of Kameoka Shrine in Nagasaki Prefecture, built in 1880, as three bays by two. The first figure runs along the ridge, the second across it.
Shrine halls carry the count in the name of their form. A hall described as one-bay Nagare-zukuri and one described as three-bay differ in size while sharing the same roof arrangement.
The word is also a unit of length. A townhouse frontage may be recorded as five and a half of them, and a storehouse at the Sakai brewery in Nagano Prefecture is recorded as about twelve long. One such unit is roughly 1.8 metres.
Traditional and metric measures side by side
The same database mixes both systems. The main hall of Tokujuji in Aichi Prefecture is recorded as 15.1 by 14.2 metres, and a building at Higashi Honganji in Kyoto as 353.56 square metres, while entries elsewhere give bays instead.
Which system appears depends on when the entry was written and what kind of property it covers. The safe course is to quote the figure as recorded and add a conversion only where it helps. Converting the traditional unit to metres without checking risks reading a count of bays as a measurement of length.
Context usually settles it. Two figures paired across the two directions of a building count bays; a single figure describing a frontage or an overall length is a measurement. Where a record gives metric dimensions as well, comparing the two resolves the ambiguity.
References
- Agency for Cultural Affairs: National Treasures and Important Cultural Properties (structures)
- https://www.bunka.go.jp/seisaku/bunkazai/shokai/yukei_kenzobutsu/kokuho_bunkazai.html
- National Cultural Properties Database: Kasuga Shrine offering hall, its round columns tied by horizontal trim and head-beams
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00009087
- National Cultural Properties Database: Kameoka Shrine Main Hall, gabled and eaves-entered, its ridge carrying crossed finials and billets
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00009404
- National Cultural Properties Database: Sakai brewery storehouse, presenting the outward form of a gatehouse with a central passage
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00003095
- National Cultural Properties Database: Tokujuji main hall, with an altar dais before a rear screen wall under a subdivided coffered ceiling
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00009292
- National Cultural Properties Database: Higashi Honganji, recorded as single-tier irimoya-zukuri with pantiles
- https://kunishitei.bunka.go.jp/bsys/maindetails/102/00005507
Last verified: 2026.08.31