Angle Converter
Convert between degrees, radians, gradians and turns in real time — handy for CSS rotate and canvas math.
>_ USAGE GUIDE
Degrees, radians, gradians and turns each own a corner of front-end work: CSS rotate() accepts all four, Canvas trigonometry takes radians only, and surveying documents occasionally surface gradians. This tool links four input fields — type in any one and the other three update live. The factor chain is worth memorizing: 1 turn = 360° = 400 grad = 2π rad.
- Type anywhere: enter a value in any unit field and the rest convert instantly
- Feed CSS: results can be used directly as
rotate(0.5turn)orrotate(200grad)— modern browsers support all four units - Feed Canvas: values from the rad column plug straight into
ctx.rotate()orMath.sin()with noMath.PI / 180multiplication - No float noise: round trips like 180° → rad → deg never show
180.00000000000003
>_ FAQ
Q1 · How many degrees is one radian?
180/π ≈ 57.2958°, and 1° = π/180 ≈ 0.01745 rad. Useful anchors: 30° = π/6, 45° = π/4, 60° = π/3, 90° = π/2, 180° = π, 360° = 2π — knowing these makes Canvas code readable without constant conversion.
Q2 · Which unit should CSS rotate() use?
Any of them — rotate(45deg), rotate(0.7854rad), rotate(50grad) and rotate(0.125turn) are equivalent. For readability, prefer deg for small angles, turn for half/whole rotations (rotate(0.5turn) says more than 180deg), and rad when the value comes straight out of a math formula.
Q3 · What is a gradian and where is it still used?
A right angle = 100 grad, a full circle = 400 grad. It survives in continental-European surveying and some engineering drawings. You will rarely need it in code, but CAD exports and legacy measurement data do contain it — supporting it prevents the silent error of reading grad as deg, which differs by a factor of 0.9.
Q4 · Why doesn't Math.sin(Math.PI / 2) need conversion?
JavaScript's trigonometric functions always take radians. Degrees must be multiplied by π/180 before any trig call, and results from Math.atan2 come back in radians — convert to deg before handing them to CSS. The rad column of this tool can be used as code as-is.
Q5 · Why do results have long decimal tails?
That is expected: π is irrational, so radian–degree conversion has no exact finite decimal representation in either direction. The tool trims display to 10 significant digits and suppresses round-trip float noise; for maximum precision keep rad as the source of truth (symbolically exact) and format only for display.