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PHYSICS EXPLAINER

LEO Satellite vs Fiber Latency

LEO is not automatically slower or faster than fiber. Fiber carries light more slowly than vacuum and may take indirect routes, while LEO paths add ground-space legs, gateways, handoffs and terrestrial backhaul.

Where LEO can help

For very long routes with efficient inter-satellite paths, vacuum propagation can offset the cost of reaching orbit.

Where fiber can win

For shorter routes with nearby peering and direct terrestrial paths, fiber avoids satellite access and gateway overhead.

QUESTIONS

Common questions

Is Starlink latency lower than fiber?

It can be lower or higher for a particular route. A fair comparison needs measured endpoints and path context.

Why is vacuum faster than fiber?

The refractive index of glass reduces the propagation speed to roughly two-thirds of the vacuum value.

Continue exploring network physics

Satellite Latency Calculator: LEO vs MEO vs GEOCompare propagation-only latency floors for LEO, MEO and GEO satellite altitudes.Fiber Latency Calculator: Distance to Ping RTTCalculate one-way fiber delay and round-trip latency from route distance. Compare an optional measured ping and check below-floor results without an ISP score.Fiber Latency per km and 1,000 km: Delay & RTTCalculate fiber latency: about 4.9 microseconds per km one way and 9.8 ms RTT per 1,000 km. Compare distances, route assumptions and measured ping.

Formula and limitations

Values use transparent approximations described in the article.

Reference constants: NIST speed of light in vacuum. Fiber propagation uses a disclosed engineering approximation of 204,000 km/s; actual group velocity varies with the fiber.