Convert km to m

キロ

定義
A kilometer (km) is a metric length unit equaling exactly 1 000 meters. In everyday terms, it corresponds to roughly 0.6214 statute miles.

背景
接頭辞キロ stems from the Greek キリオイ (“thousand”), making the kilometer simply a thousandfold multiple of the meter. Today, the meter—and by extension the kilometer—is defined by the distance light covers in 1 / 299 792 458 seconds, ensuring an unchanging standard.

使用場所
Kilometers are the world’s default for mapping and road signage, public transit, marathon distances, and more. Although countries like the United States and Liberia still use miles on highways, most of the globe—including Canada, Europe, Asia, and Australia—relies on kilometers for land‐distance measurements.

メーター

定義
A meter (m) is the SI’s base unit of length. It’s defined by the fixed speed of light: one meter is the distance light travels in a vacuum in 1 / 299 792 458 of a second. This modern definition, adopted in 1983 and refined in 2019 alongside the second, underpins global measurement consistency.

背景

1793: 赤道から北極までの距離の1000万分の1と定義される。
1889: 0℃で白金-イリジウムのプロトタイプバーにより実現。
1960: Recast in terms of krypton-86 wavelengths.
1983-2019: Anchored to the speed of light, ensuring absolute precision.

使用場所
Meters are ubiquitous—from architectural blueprints and engineering schematics to everyday tasks like measuring room dimensions or tracking growth on a height chart. Even in countries that favor customary units, meters remain the scientific and trade standard.