Convert between degrees, radians, gradians, turns, arcminutes and arcseconds. The radian is the natural unit of calculus — sin(x) only has derivative cos(x) when x is in radians — while degrees rule everyday geometry.
Full turn: 360° = 2π rad = 400 grad. Arcminutes and arcseconds subdivide each degree by 60 — the notation used for celestial coordinates and lens fields of view.
Frequently asked questions
Why do programming languages want radians?
Math.sin and friends are defined on radians so their Taylor series and derivatives are clean; multiply degrees by π/180 first.
What is 1 radian in degrees?
About 57.2958° — the angle where the arc length equals the radius.
中文说明
在度、弧度、百分度、转数、角分与角秒之间换算。弧度是微积分的自然单位——只有 x 以弧度计，sin(x) 的导数才是 cos(x)——而日常几何用度。
一整圈：360° = 2π rad = 400 grad。角分与角秒把每度按 60 细分，是天体坐标与镜头视场角的记法。
常见问题
为什么编程语言都用弧度？
Math.sin 等函数按弧度定义，泰勒展开与求导才干净；先把角度乘以 π/180 再传入。
1 弧度等于多少度？
约 57.2958°——即弧长恰好等于半径时所对的圆心角。