🌌Hubble's Law Calculator
Apply v = H₀ × d to find a galaxy's recession velocity or distance, with an adjustable Hubble constant reflecting real measurement uncertainty.
The Hubble constant is still debated — measurements range roughly 67–73 km/s/Mpc, a discrepancy known as the "Hubble tension." Adjust the slider to see its effect.
Free Hubble's Law Calculator
Want to see the expanding universe in action? Our free Hubble's Law Calculator applies v = H₀ × d to find how fast a galaxy is receding from us based on its distance, or work backward from a measured velocity to find distance. Adjust the Hubble constant across its real measured range (67–73 km/s/Mpc) to see how the ongoing "Hubble tension" debate affects the numbers.
Enter a distance in megaparsecs, million light-years, or light-years, and get recession velocity in km/s — plus a comparison to the speed of light for very distant objects. A few real preset galaxies help ground the numbers, along with a note on why Andromeda is a special exception that's actually moving toward us.
No sign-up, no downloads, no limits. See the About page or the FAQ for more.
About the Hubble's Law Calculator
Features
Solve for distance or velocity
Switch direction depending on which quantity you already know.
Adjustable Hubble constant
Slide across the real measured range (67–73 km/s/Mpc) to see the Hubble tension's effect on results.
Unit handling for Mpc/ly
Enter distance in megaparsecs, million light-years, or light-years.
v/c comparison
See recession velocity as a fraction of the speed of light for very distant galaxies.
Frequently Asked Questions
What is Hubble's law?
A relation stating that a galaxy's recession velocity is proportional to its distance from us: v = H0 × d.
How does this calculator work?
Enter either distance or recession velocity, choose a Hubble constant value, and it solves for the missing quantity.
Is it free?
Completely free, no sign-up, downloads, or limits.
What is the Hubble constant?
A measure of the universe's expansion rate, roughly 67–73 km/s per megaparsec depending on the measurement method — a discrepancy known as the Hubble tension.
Why is Andromeda not included as a typical example?
Andromeda is gravitationally bound to the Milky Way and actually approaching us, so Hubble's law, which describes large-scale cosmic expansion, doesn't apply to it.
Can I use light-years instead of megaparsecs?
Yes, distance can be entered in Mpc, million light-years, or light-years.
What does v/c mean in the results?
It shows the recession velocity as a fraction of the speed of light, useful for very distant, fast-receding galaxies.
What happens with negative distance or velocity?
The calculator rejects negative values with a clear message.
Is my data stored?
No; everything runs in your browser and isn't stored or sent anywhere.
Does it work on mobile?
Yes, fully responsive on all screen sizes.