How to convert degrees to radians in JavaScript
Łukasz HoleczekFollow Łukasz Holeczek on GitHubConnect with Łukasz Holeczek on LinkedInFollow Łukasz Holeczek on X (Twitter)Converting degrees to radians is crucial for trigonometric functions, mathematical calculations, animation rotations, and implementing features like canvas graphics or geometric transformations in JavaScript applications.With over 25 years of experience in software development and as the creator of CoreUI, I’ve implemented degree-to-radian conversion in components like chart rotations, animation systems, and mathematical utilities where JavaScript’s trigonometric functions require radian input for accurate calculations.From my extensive expertise, the standard mathematical approach is multiplying degrees by π/180, using JavaScript’sMath.PI constant for precision.This conversion is essential since JavaScript’s trigonometric functions (sin, cos, tan) expect radian values rather than degrees.
Multiply degrees by π/180 to convert to radians.
constdegrees=90constradians=degrees*(Math.PI/180)// Result: 1.5707963267948966 (π/2)constdegreesToRadians=(deg)=>deg*(Math.PI/180)// Usage: degreesToRadians(180) returns π (3.141592653589793)The conversion formuladegrees * (Math.PI / 180) is based on the mathematical relationship that 180 degrees equals π radians. In this example, 90 degrees converts to π/2 radians (approximately 1.57), which is the correct input forMath.sin(radians) to return 1. The function version provides a reusable converter for any degree value. Common conversions: 90° = π/2 radians, 180° = π radians, 360° = 2π radians. This conversion is necessary because JavaScript’sMath.sin(),Math.cos(), andMath.tan() functions require radian inputs.
Best Practice Note:
This is the same approach we use in CoreUI components for trigonometric calculations, animation rotations, and geometric transformations across our component library.Create a utility function for reusability:const toRadians = deg => deg * Math.PI / 180. Always convert degrees to radians before using trigonometric functions. The inverse conversion usesradians * (180 / Math.PI). This conversion is fundamental for any application involving angles, rotations, or trigonometric calculations in JavaScript.
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About the Author
Łukasz Holeczek, Founder of CoreUI, is a seasoned Fullstack Developer and entrepreneur with over 25 years of experience. As the lead developer for all JavaScript, React.js, and Vue.js products at CoreUI, they specialize in creating open-source solutions that empower developers to build better and more accessible user interfaces.
With expertise in TypeScript, JavaScript, Node.js, and modern frameworks like React.js, Vue.js, and Next.js, Łukasz combines technical mastery with a passion for UI/UX design and accessibility. CoreUI’s mission is to provide developers with tools that enhance productivity while adhering to accessibility standards.
Łukasz shares its extensive knowledge through a blog with technical software development articles. It also advises enterprise companies on building solutions from A to Z. Through CoreUI, it offers professional services, technical support, and open-core products that help developers and businesses achieve their goals.
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