Convert inches to meters

インチ

定義
An inch (symbol: in) is a length unit in the Imperial and U.S. customary systems. Since 1959, it’s been locked at exactly 25.4 mm. Each foot holds 12 inches, and each yard spans 36 inches.

起源
The term “inch” stems from the Latin ウンシア (“one-twelfth”), originally denoting one-twelfth of a Roman foot. Early measures tied an inch to three barleycorns laid end-to-end or the average width of three thumbs, before standardization against the international yard.

現代の使用
Inches remain the standard in the U.S., Canada, and U.K. for everyday tasks—carpentry, hardware sizing, and screen diagonals. Electronics manufacturers worldwide also specify monitor and smartphone sizes in inches.

メーター

定義
A meter (symbol: m) is the SI base unit of length, defined as the distance light travels in a vacuum in 1 / 299 792 458 of a second. This constant-based definition, adopted in 1983 and refined in 2019, ensures unchanging accuracy.

起源

1793: One ten-millionth of the Earth’s quadrant from Equator to North Pole
1889: Length of a platinum–iridium prototype bar at 0 °C
1960: Defined by a specific number of krypton-86 emission wavelengths
1983-2019: 光速に固定される

現代の使用
Meters dominate global measurements—in science, engineering, construction, and distance signage (outside the U.S.), while feet and inches persist in daily life in a few countries.