Relativistic Doppler Factor Calculator

Use the longitudinal special-relativistic Doppler factor with positive beta defined as recession. Unlike classical sound Doppler shift, no propagation-medium speed is entered. The calculator evaluates only the stated idealized equation and supplied values. It does not infer missing conditions, choose an experimental convention, or certify a measurement. Keep every quantity in the displayed unit and verify the model against the physical setup before relying on the result.

Factors below one are redshifts under the stated recession convention; negative beta produces approach and a factor above one. Changing the sign reverses approach and recession under this convention. Numerical precision does not imply experimental accuracy. Compare the output with scale, sign, limiting cases, and an independent source, then account for uncertainty in measured inputs and constants before using it in laboratory, engineering, or safety-sensitive work.

Motion is directly along the line of sight in flat spacetime and |v| is less than c. It excludes transverse geometry, cosmological expansion, gravity, acceleration, and refractive media. The result is educational and is not a simulation, calibration, engineering approval, or safety determination. More complete models may require geometry, material response, boundary conditions, relativistic frames, dispersion, losses, uncertainty propagation, or numerical field solutions not represented by these inputs.