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Relativistic Velocity Addition Calculator

Adds two velocities correctly under special relativity so the result never exceeds the speed of light. Essential when objects move at a significant fraction of c.

First Velocity (m/s)

Second Velocity (m/s)

Fill in the required fields to see your result.

Relativity

Relativistic Doppler Shift Calculator

Calculates the observed frequency of light or sound when source and observer move at relativistic speeds. Use it when relative velocity is a significant fraction of the speed of light.

Rest Frequency (Hz)

Relative Velocity (m/s)

Direction

Fill in the required fields to see your result.

Key differences

	Relativistic Velocity Addition Calculator	Relativistic Doppler Shift Calculator
Category	Relativity	Relativity
Inputs required	2	3
Result	Combined Velocity (m/s)	Observed Frequency (Hz)
What it does	Adds two velocities correctly under special relativity so the result never exceeds the speed of light. Essential when objects move at a significant fraction of c.	Calculates the observed frequency of light or sound when source and observer move at relativistic speeds. Use it when relative velocity is a significant fraction of the speed of light.