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Ken (unit)

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A ken is a traditional unit of length used in Japan.

Tōdai-ji Kon-dō
Tōdai-ji Kon-dō

It is equal to six shaku, which are Japanese feet. Today, the standard length is exactly 1.82 meters. This measurement is very important for Japanese architecture. Builders use it to plan the space between pillars. In this job, a ken is often called a "bay."

Moya hisashi
Moya hisashi

This unit helps make buildings look balanced and right.

Architects use the ken to create the shape of a building. They often use an odd number of bays, like 3x3 or 5x5. Some temple gates, called rōmon, can be as small as 1x1 bay. A Zen building called a butsuden might have a 5x5 ken exterior. This happens when a 3x3 ken core, or moya, has an aisle called a hisashi around it.

Moya hisashi
Moya hisashi

The ken helps decide how much space people have to walk or pray.

History shows that the ken has changed over many years. It is based on the Chinese jian. Long ago, people needed to measure land to calculate taxes. During the 16th century, the ken was about 1.91 meters long. Around 1650, the Tokugawa shogunate changed it to 1.81 meters. This change helped them collect more taxes from the land.

Tōdai-ji Kon-dō
Tōdai-ji Kon-dō

Even though the size changed, it was often kept the same within one building.

There are many specific places where the ken is used today. The Enryaku-ji Konponchū-dō hall measures 11x6 bays. This is about 37.60 meters by 23.92 meters. At the Izumo Taisha shrine, the ken is much larger than the standard size. At Kasuga Taisha, a tiny building is only 1x1 ken.

Tōdai-ji Kon-dō
Tōdai-ji Kon-dō

These different sizes show how flexible the unit can be in different settings.

The ken is linked to many common items in Japan. It sets the standard length for a bō staff in martial arts. It also tells us the size of tatami mats on the floor. One tatami mat is exactly half of a square ken.

Japanese ryakuji KAN
Japanese ryakuji KAN

The name comes from a character showing a door and the sun. This character is also used for the word ma, which means space or a pause.

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🖼️ Images & Media (3)
File:Moya hisashi.svg
Moya hisashi.svg
File:Japanese ryakuji KAN.png
Japanese ryakuji KAN.png
File:Tōdai-ji Kon-dō.jpg
Tōdai-ji Kon-dō.jpg
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