How fast does the ISS travel?

At its standard altitude of about 408 km, the ISS travels at roughly 7.66 km/s (27,576 km/h or about 17,136 mph). This speed is necessary to maintain a stable circular orbit without falling back to Earth.

Why does orbital speed decrease at higher altitudes?

Gravity weakens with distance. At higher altitudes the gravitational pull is weaker, so less centripetal force — and therefore less speed — is needed to maintain a circular orbit. The relationship is v = sqrt(GM/r), so speed decreases as orbital radius increases.

How many times does the ISS orbit Earth each day?

At 408 km altitude the ISS completes roughly 15.5 orbits per day (about one orbit every 92–93 minutes). Not every orbit results in a visible pass from a given ground location.

What is the lowest safe orbital altitude?

Below about 200 km, atmospheric drag is significant enough to deorbit a spacecraft within days or hours. The ISS periodically boosts its orbit to counteract the slow drag at 400 km altitude.

Does this formula work for other satellites?

Yes. The circular orbit formulas v = sqrt(GM/r) and T = 2pi*sqrt(r^3/GM) apply to any satellite orbiting Earth, from the ISS to GPS satellites (20,200 km) and geostationary satellites (35,786 km). Just change the altitude input.

What is GM for Earth?

GM (the standard gravitational parameter for Earth) is approximately 3.986 x 10^14 m^3/s^2. It combines the gravitational constant G = 6.674 x 10^-11 N*m^2/kg^2 with Earth's mass of about 5.972 x 10^24 kg.

ISS Speed Calculator

Name: ISS Speed Calculator
Availability: InStock
Author: Nham Vu

Enter the ISS altitude to instantly compute its orbital speed, period, passes per day, and distance covered.

Orbital Parameters

Quick Presets

Altitude above Earth (km)

Valid range: 200 – 2000 km

Speed: v = √(GM/r)
Period: T = 2π√(r³/GM)
GM = 3.986 × 10¹⁴ m³/s²

Orbital Speed

408 km altitude

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vs. ISS at 408 km (27,576 km/h)

Period

Passes / Day

Orbital Radius

Dist / Orbit

Perspective

Sunrises per day

Speed vs. sound

Distance per day

Time to circle Earth

Altitude Comparison

Satellite / Orbit	Alt (km)	Speed (km/s)	Period (min)

Summary

Enter the ISS altitude to instantly compute its orbital speed, period, passes per day, and distance covered.

How it works

Enter an orbital altitude in kilometers (default: 408 km, the ISS average altitude).
The calculator adds Earth's radius (6371 km) to get the orbital radius r.
Orbital speed is computed as v = sqrt(GM / r), where GM = 3.986 x 10^14 m^3/s^2.
Orbital period is computed as T = 2pi * sqrt(r^3 / GM), then converted to minutes.
Passes per day = 1440 minutes divided by the orbital period in minutes.
Distance per orbit = orbital speed multiplied by the period.

Use cases

Learn how fast the ISS travels and why astronauts see 16 sunrises per day.
Compare orbital speed at different altitudes for physics education.
Estimate when the ISS passes overhead by knowing its orbital period.
Understand how altitude trade-offs affect speed and revisit frequency.
Explore orbital decay: lower orbits are faster but have more atmospheric drag.
Prepare for space science exams or astronomy olympiad competitions.
Visualize satellite constellation design trade-offs (LEO vs MEO).
Calculate how far an object travels in a single orbit.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu