Work out degrees to radians instantly with clear inputs, formula shown and shareable results.
A full circle is 360° or 2π radians, so one degree equals π/180 radians. Multiplying by π/180 converts degrees to radians; multiplying by 180/π reverses it.
Degrees to radians
radians = degrees × π / 180
90 × π/180 = π/2 ≈ 1.570796 radians.
The derivative of sin x is cos x only when x is in radians; in degrees an extra factor of π/180 appears.