Video tutorial

视频教程

The trouble with units

单位的麻烦

Most unit conversions are simple multiplication by a constant — meters to feet, kilograms to pounds. The exceptions are temperature (which has an offset as well as a multiplier) and time (where months and years vary in length). This tool handles both correctly.

大多数单位换算只是简单乘以一个常数 —— 米到英尺、公斤到磅。例外是温度（既有偏移又有系数）和时间（月份和年份长度不固定）。本工具对两种情况都做了正确处理。

The Mars Climate Orbiter was lost in 1999 because one team used metric units and another used imperial — a $327 million lesson in why you should always label your units.

1999 年火星气候探测器坠毁，原因是两个团队分别使用公制和英制单位 —— 这是 3.27 亿美元代价换来的教训，提醒我们永远要标注单位。