Ken to Millimeters (ken to mm)

1 ken equals 1,818.181818 millimeters (rounded).

1 ken = 1,818.181818 millimeters

How to convert ken to millimeters

To convert ken to millimeters, multiply the number of ken by 1,818.181818. The factor is rounded to 10 significant digits. To go the other way, multiply millimeters by 0.00055.

millimeters = ken × 1,818.181818

Example: 10 ken = 18,181.81818 millimeters.

About these units

Ken (ken)

JapaneseTraditional unit (still used in some regions)

Six shaku, exactly 20/11 meter (about 1.818 m). The traditional spacing of pillars in Japanese buildings; a tatami mat is half a ken wide in the Nagoya size.

Ken is the Japanese reading of the Chinese character jian, which means room, gap or interval. The name fits its job: the distance between two pillars of a building became a unit of measure, and land surveyors then used it when assessing taxes.

Its size has not always been the same. Under Toyotomi Hideyoshi in the 16th century it was about 1.97 meters, but around 1650 the Tokugawa shogunate shortened it to 1.818 meters, which raised the tax take. Since 1891 it has been exactly six shaku, or 20/11 meter. The longer old measure lives on in the Kyoto room size called kyoma.

Floor plans still lean on the ken. A tatami mat measures one half ken by one ken in the common Nagoya size, and a square ken of floor is a tsubo, about 3.31 square meters. The ken also fixes the length of the bo staff in Japanese martial arts.

1 ken = 1.818181818 meters (approximately).

Sources: Wikipedia: Ken (unit); Wikipedia: Tatami; Wikipedia: Japanese units of measurement

Millimeter (mm)

Metric (SI)Current unit

One thousandth of a meter. Used in engineering, manufacturing and rainfall measurement.

Carl Friedrich Gauss put the millimeter at the base of his 1832 proposal for absolute units, pairing it with the milligram and the second, although the centimeter-based CGS system later won out among scientists. The name combines the metric prefix milli-, from the Latin for one thousand, with the meter. Since 1983 a millimeter has been tied to the speed of light: it is the distance light covers in 1/299,792,458,000 of a second.

Millimeters are the language of fine mechanical work. Standard rulers are divided into them, digital calipers commonly read to 0.01 mm, and mechanical pencil leads come in 0.5 and 0.7 mm. Copy paper is about 0.1 mm thick, and a thin hair, at 0.02 to 0.04 mm across, is close to the smallest thing the naked eye can see. A wave with a frequency of 300 GHz has a wavelength of 1 mm. An inch is exactly 25.4 mm. One trap for readers in the United States is that mil there traditionally means a thousandth of an inch, not a millimeter.

1 millimeter = 0.001 meters (exactly).

Sources: Wikipedia: Millimetre; Wikipedia: Centimetre-gram-second system of units; NIST Guide to the SI, Appendix B.8: conversion factors

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