🚗 千米/天 ↔ 光速Kilometre/day to Speed of light
千米/天与光速互算（1 km/d = 3.86069554627e-11 c）。本地换算，附常用相关单位。Convert kilometre/day and speed of light (1 km/d = 3.86069554627e-11 c). Runs locally with related units.
点击任意一行可复制该结果；小于 0.0001 或不小于 10¹⁵ 的数值用 × 10ⁿ 科学计数法显示Click any row to copy that result. Values below 0.0001 or at least 10¹⁵ are shown in × 10ⁿ notation
使用说明与常见问题How-to & FAQ
「千米/天 ↔ 光速」是什么？What is the Kilometre/day to Speed of light tool?
千米/天与光速互算（1 km/d = 3.86069554627e-11 c）。本地换算，附常用相关单位。Convert kilometre/day and speed of light (1 km/d = 3.86069554627e-11 c). Runs locally with related units.
如何使用「千米/天 ↔ 光速」？How do I use the Kilometre/day to Speed of light tool?
在「千米/天 ↔ 光速」中输入数值并选择原单位，表格会同时列出换算到所有其他单位的结果，可一键复制。Enter a value in the Kilometre/day to Speed of light and choose the source unit; the table shows the value in every other unit at once, ready to copy.
1 千米/天等于多少光速？How many speed of light in 1 kilometre/day?
1 km/d = 3.86069554627e-11 c（按国际定义系数）。1 km/d = 3.86069554627e-11 c (international definition).
如何把千米/天换算成光速？How do I convert kilometre/day to speed of light?
结果 = 数值 × 3.86069554627e-11。例如 25902068371.2 km/d = 1 c。result = value × 3.86069554627e-11. Example: 25902068371.2 km/d = 1 c.
千米/天/光速属于哪类单位？What kind of units are kilometre/day/speed of light?
二者同属「速度」量纲，可安全互算；也可打开「speed-converter」做多单位对照。Both are speed units; see also the speed converter hub.
换算系数准确吗？Are the conversion factors exact?
「千米/天 ↔ 光速」采用国际单位制（SI）或公认标准中的定义值作为换算系数，结果保留约 10 位有效数字。The Kilometre/day to Speed of light uses factors defined by the SI or other recognised standards and shows about 10 significant digits.
「千米/天 ↔ 光速」免费吗？需要注册吗？Is the Kilometre/day to Speed of light free? Do I need an account?
「千米/天 ↔ 光速」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Kilometre/day to Speed of light is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.