Satellite Speed Calculator Formula

Understand the math behind the satellite speed calculator. Each variable explained with a worked example.

Use the Satellite Speed Calculator

Formulas Used

Orbital Speed

speed = sqrt(3.986e14 / ((6371 + altitude) * 1000))

Speed (km/s)

speed_kmps = sqrt(3.986e14 / ((6371 + altitude) * 1000)) / 1000

Orbital Period

period_min = 2 * pi * sqrt(pow((6371 + altitude) * 1000, 3) / 3.986e14) / 60

Variables

VariableDescriptionDefault
altitudeAltitude Above Surface(km)400

How It Works

Satellite Speed From Altitude

v = √(GM / r) where r = R_Earth + altitude

Using GM_Earth = 3.986e14 m³/s² and R_Earth = 6371 km.

The period follows: T = 2πr / v

Worked Example

Find the speed of the ISS at 400 km altitude.

altitude = 400
  1. 01r = 6371 + 400 = 6771 km = 6 771 000 m
  2. 02v = √(3.986e14 / 6 771 000) ≈ 7 673 m/s
  3. 03Period = 2π × 6 771 000 / 7 673 ≈ 5 542 s ≈ 92.4 min

Ready to run the numbers?

Open Satellite Speed Calculator