How to use the relativistic velocity addition calculator
Add two velocities using special relativity. Enter velocity 1 (fraction of c), velocity 2 (fraction of c) in the fields above; the combined velocity is computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “speed of light addition”, “spaceship fires missile”, “combine velocities”, “calculate relativistic velocity addition”, “find combined velocity”.
Formula
Variables
- u — Velocity 1 (fraction of c)
- v — Velocity 2 (fraction of c)
Worked example
With velocity 1 (fraction of c) = 0.8, velocity 2 (fraction of c) = 0.8, the calculator gives combined velocity ≈ 0.9756098 c.
Frequently asked questions
What is the relativistic velocity addition calculator used for?
Add two velocities using special relativity. It helps with questions such as “speed of light addition”, “spaceship fires missile”, “combine velocities”.
What is the formula for the relativistic velocity addition calculation?
Combined velocity (c) = (u+v) / (1+u × v). Here u is velocity 1 (fraction of c), v is velocity 2 (fraction of c).
What inputs do I need for the relativistic velocity addition calculator?
You need velocity 1 (fraction of c), velocity 2 (fraction of c). Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the relativistic velocity addition calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the relativistic velocity addition result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.