Hohmann Transfer Orbit Calculator
Fill in the values and the answer updates as you type.
How the Hohmann Transfer Orbit Calculator works
A Hohmann transfer is the lowest-energy path between two circular orbits around the Sun, an ellipse that touches both. Its semi-major axis = (r1 + r2) ÷ 2, and the trip takes half of one orbit: time = 0.5 × axis^1.5 years. The two burns use circular speeds of 29.78 ÷ √r km/s. The result is the heliocentric velocity change only. Leaving and entering a planet gravity well costs more. Earth to Mars uses 1 and 1.524 AU. Example: with Departure orbit radius 1 AU and Arrival orbit radius 1.524 AU, the result is Transfer time (days) = 258.91; Transfer time (years) = 0.71; Total velocity change (km/s) = 5.6.
Inputs and results
The Hohmann Transfer Orbit Calculator takes 2 inputs and gives 4 results.
What you enter
- Departure orbit radius (AU) — starts at 1.
- Arrival orbit radius (AU) — starts at 1.524.
What you get
- Transfer time (days)
- Transfer time (years)
- Total velocity change (km/s)
- Transfer orbit semi-major axis (AU)
Example: Hohmann Transfer Orbit Calculator with the starting values
With departure orbit radius 1 AU and arrival orbit radius 1.524 AU, the calculator returns:
| Transfer time (days) | 258.91 |
|---|---|
| Transfer time (years) | 0.71 |
| Total velocity change (km/s) | 5.6 |
| Transfer orbit semi-major axis (AU) | 1.26 |
Change any value above and the results update straight away.
Hohmann Transfer Orbit Calculator FAQ
How do I use the Hohmann Transfer Orbit Calculator?
Enter departure orbit radius and arrival orbit radius in the fields, then read transfer time (days), transfer time (years), total velocity change (km/s) and transfer orbit semi-major axis (au) in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Hohmann Transfer Orbit Calculator calculate?
Travel time and velocity change to move between two planetary orbits. It returns transfer time (days), transfer time (years), total velocity change (km/s) and transfer orbit semi-major axis (au) from the 2 values you provide.
What values does the Hohmann Transfer Orbit Calculator start with?
It opens with departure orbit radius 1 AU and arrival orbit radius 1.524 AU so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Hohmann Transfer Orbit Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Hohmann Transfer Orbit Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.