Compare calculators
Both calculators run independently — change the inputs on either side to compare results.
Astronomy
Redshift Velocity Calculator
Compute the recession velocity of a nearby galaxy from its redshift z using v = c·z, where c is the speed of light. Part of the Hubble-Lemaître law — the empirical relation that established the expanding universe.
Fill in the required fields to see your result.
Astronomy
Orbital Velocity Calculator
Compute the orbital velocity around a central body using v = √(GM/r) × √(1+e), an approximation that scales the circular-orbit speed by the eccentricity. Useful for first-order estimates of satellite velocities, planetary orbital speeds, and binary star systems.
Fill in the required fields to see your result.
Key differences
| Redshift Velocity Calculator | Orbital Velocity Calculator | |
|---|---|---|
| Category | Astronomy | Astronomy |
| Inputs required | 1 | 3 |
| Result | Recession Velocity (km/s) | Orbital Velocity (m/s) |
| What it does | Compute the recession velocity of a nearby galaxy from its redshift z using v = c·z, where c is the speed of light. Part of the Hubble-Lemaître law — the empirical relation that established the expanding universe. | Compute the orbital velocity around a central body using v = √(GM/r) × √(1+e), an approximation that scales the circular-orbit speed by the eccentricity. Useful for first-order estimates of satellite velocities, planetary orbital speeds, and binary star systems. |