Degrees ↔ Radians Converter
Convert an angle from degrees to radians or from radians to degrees.
Calculator
Use the Degrees ↔ Radians Converter
Result
—
Formula
rad = deg × π ÷ 180
Step-by-step
- 1
Enter the angle
The value to convert.
- 2
Pick the direction
deg→rad or rad→deg.
Worked example
Example input: angle: 180, mode: deg2rad
Result: 3.14159265
Related tools
- Sine Calculator
Works in both units.
Frequently asked questions
How do you convert degrees to radians?
Multiply by π and divide by 180: radians = degrees × π ÷ 180. A half turn of 180° becomes π radians (about 3.14159).
Can it convert in the other direction too?
Yes — flip the direction selector to rad2deg and the calculator multiplies by 180/π instead. For example, 2 radians ≈ 114.5916°.
Why is a full circle 2π radians?
One radian is the angle whose arc length equals the radius. Walking the entire circumference of 2πr therefore takes 2π of those arcs, which is why 360° = 2π rad.
Why do mathematicians prefer radians?
Because radians connect the angle directly to arc length: 1 radian cuts exactly one radius worth of arc from the circle. Formulas such as arc = rθ and the small-angle sin θ ≈ θ only stay clean in radians, which is why calculus defaults to them.