How fast does a rocket actually go?
Slower than you think at first, and far faster than you think at the end. The speeds at every stage of a launch, and why sideways is the number that matters.
5 min read
The moment a rocket releases its clamps it is at its heaviest, and it rises slowly enough that you can watch it clear the tower. Eight and a half minutes later it is going 27,600 km/h. Here is what happens in between.
The numbers, from a real flight
- Liftoff: 0 km/h. The rocket barely moves for the first second.
- About 70 seconds — Max Q: roughly 1,500 km/h, and the roughest part of the ride.
- Two minutes 26 — engines cut off: about 8,300 km/h, 68 km up.
- Eight minutes 39 — in orbit: about 27,600 km/h.
Why the start is so slow
At liftoff the rocket is carrying every kilogram of propellant it will ever burn. Thrust exceeds weight, but not by much — a Falcon 9 leaves the pad with a thrust-to-weight ratio around 1.4, so the initial acceleration is only about 0.4 g.
It gets easier every second. As propellant burns off the rocket gets lighter while the engines keep pushing just as hard, so acceleration climbs steadily. By the end of the first stage the crew of a Dragon would be feeling several times their own weight.
The number that actually matters
Getting high is easy. A balloon can reach 40 km. What costs the fuel is going sideways fast enough to stay up.
At the space station’s altitude of about 420 km you need roughly 7.7 km/s — 27,600 km/h — travelling parallel to the ground. At that speed the Earth curves away beneath you as fast as gravity pulls you down, so you fall forever without landing.
A useful way to feel it: the station goes right around the planet every 92.9 minutes, and its crew sees fifteen and a half sunrises a day.
How that compares
- A car on a motorway: about 110 km/h.
- A passenger jet: about 900 km/h.
- Concorde: about 2,200 km/h.
- A Falcon 9 at stage separation: about 8,300 km/h.
- Anything in low Earth orbit: about 27,600 km/h.
The last line is roughly thirty times a passenger jet. It is also why re-entry is so violent — all of that speed has to be turned into heat before anything can land.
Common questions
How fast does a rocket go to reach orbit?
About 27,600 km/h, or 7.7 km per second, travelling sideways. Height is the easy part; that horizontal speed is what keeps a spacecraft from falling back.
How fast is a rocket at liftoff?
Barely moving. A Falcon 9 leaves the pad with a thrust-to-weight ratio around 1.4, giving about 0.4 g of acceleration, because it is carrying all of its propellant at that moment.
How long does it take a rocket to reach orbit?
About eight and a half minutes. On a typical Falcon 9 flight the second stage shuts down at 8 minutes 39 seconds, at which point the payload is in orbit.