Why Your Ping to the Other Side of the World Can Never Go Below ~150ms: The Speed-of-Light Floor

No amount of network upgrades will get your ping to a server on the other side of the world below about 130-150ms — not because of congestion, old equipment, or your ISP, but because of the speed of light, which sets a hard physical floor on latency that no technology can improve past

The previous articles on this site covered ping basics, latency/jitter/packet loss, the ping-to-port-scan diagnostic workflow, and ICMP fundamentals. This article addresses the physical floor on latency — why ping times to distant servers have a minimum possible value that's determined by geography and physics, regardless of network quality — and what this means for interpreting ping results to servers in different regions.

The speed of light in fiber: slower than in a vacuum, but still the limiting factor

Light travels at approximately 300,000 km/second in a vacuum — but in fiber-optic cable (the medium most long-distance internet traffic travels through), light travels at roughly 2/3 of that speed — approximately 200,000 km/second — due to the refractive index of the glass fiber.

This means: a signal traveling through fiber from Point A to Point B takes a minimum time determined by the distance between A and B, divided by ~200,000 km/s — and ping measures a round trip (signal travels to the destination, and back) — so the minimum possible ping time is (distance × 2) ÷ 200,000 km/s.

Worked examples: distance-based minimum pings

New York to London (~5,500 km): minimum round-trip = (5,500 × 2) ÷ 200,000 = 0.055 seconds = 55ms

New York to Tokyo (~10,800 km): minimum round-trip = (10,800 × 2) ÷ 200,000 = 0.108 seconds = 108ms

New York to Sydney (~16,000 km): minimum round-trip = (16,000 × 2) �τ 200,000 = 0.16 seconds = 160ms

These are theoretical minimums — assuming a perfectly straight, direct fiber path, with zero additional delay from equipment along the way (routers, switches — each adds some small processing delay, covered in the previous "what your ping number means" article as part of overall latency). Real-world pings to these distances are always somewhat higher than these theoretical minimums — but never lower — the theoretical minimum represents an absolute floor.

Why fiber routes aren't straight lines — and why this matters

Undersea fiber cables, and terrestrial fiber routes generally, follow practical paths — dictated by geography (avoiding certain terrain), existing infrastructure (routing through specific data center hubs, even if that's not the geometrically shortest path), and political/economic factors (which countries cables land in, agreements between operators).

A "great circle" route (the geometrically shortest path between two points on a sphere) is rarely the actual fiber route — real cables typically follow paths that are longer than the great-circle distance — sometimes significantly so, depending on the specific route and region.

This means: the "theoretical minimum" calculated from great-circle distance is itself often an underestimate of the true physical minimum — the actual fiber path length (which determines the true physical floor) is generally somewhat longer than the great-circle distance — real-world "best achievable" pings, for a given pair of locations, reflect the actual fiber route's length, not the great-circle distance — which is part of why "calculated theoretical minimums" (using great-circle distance) should be treated as a lower bound on the lower bound — the true achievable minimum is, in practice, somewhat higher.

Satellite internet: a different latency profile entirely

Traditional geostationary satellite internet — satellites positioned at extremely high altitude (~36,000 km above Earth's surface) — involves a signal traveling up to the satellite, and back down, for each direction of communication — a round trip involving four such "up-and-down" legs (your device → satellite → ground station → ... → ground station → satellite → your device, roughly) — at 36,000 km per leg, even at the speed of light, this adds hundreds of milliseconds of latency — geostationary satellite internet has historically been associated with noticeably higher latency than terrestrial (fiber/cable) connections, for this fundamental, altitude-driven reason.

Lower-orbit satellite systems (positioned at much lower altitudes, hundreds of km rather than tens of thousands) involve a much shorter signal path per hop — substantially reducing the satellite-specific latency penalty, compared to geostationary systems — though such systems introduce their own additional considerations (signal handoffs between satellites as they move relative to the ground, for instance) that are beyond the scope of this article's speed-of-light focus.

What this means for interpreting ping results to different servers

If you ping a server geographically close to you, and get, say, 10ms — and ping a server on a different continent, and get 150ms — the 150ms isn't necessarily "your connection to that server is bad" — it may simply reflect the physical distance — which no network configuration, on either end, can reduce below the distance-determined floor.

Comparing your ping to a distant server against someone else's ping to the same server, from a different location — differences primarily reflect each person's respective distance to that server — not a meaningful comparison of "whose connection is better," unless both people are roughly equidistant from the server (in which case, differences would more likely reflect local network factors, rather than the physical-distance floor, which would be similar for both).

For services where low latency matters (real-time gaming, video calls, etc. — touched on in the previous "what ping means" article) — choosing servers/services geographically closer to you provides a lower latency floor — no amount of local-network optimization can overcome the physical-distance penalty of connecting to a server on the opposite side of the world, if a geographically closer alternative exists.

How to use the Ping Tool on sadiqbd.com

1. For servers geographically close to you: ping times are primarily influenced by local network factors (your connection, the server's hosting infrastructure, intermediate routing) — the physical-distance floor is small and generally not the dominant factor
2. For servers on other continents: recognize that a substantial baseline — determined by distance — is unavoidable — compare your measured ping against a rough, distance-based expectation (using the great-circle-distance calculation above, keeping in mind real routes are typically somewhat longer) — pings meaningfully higher than this rough expectation may indicate room for improvement (suboptimal routing, congestion); pings close to the distance-based expectation are likely near the practical floor for that route
3. When choosing between servers for latency-sensitive applications: geographic proximity provides a hard, physics-based advantage that no amount of other optimization can overcome — all else being roughly equal, closer is, fundamentally, better, for latency

Frequently Asked Questions

Could future technology ever reduce latency below the speed-of-light-in-fiber limit? Not via fiber, by definition — the speed of light in fiber (200,000 km/s) is a property of the physical medium; it's not expected to change. Some research has explored hollow-core fiber (where light travels through air/vacuum within the fiber, rather than through glass — air/vacuum allows light to travel closer to its full, vacuum speed of 300,000 km/s, rather than the *200,000 km/s of conventional glass fiber) — which, if deployed at scale, could reduce the speed-of-light-in-medium factor somewhat (closer to the vacuum speed) — but even this wouldn't eliminate the distance-based floor entirely — it would shift the floor closer to the vacuum-speed-based calculation (300,000 km/s instead of ~200,000 km/s), but a floor, determined by distance, would still exist — the speed of light itself (in vacuum) represents the ultimate, unbreakable physical limit, regardless of medium.

Is the Ping Tool free? Yes — completely free, no sign-up required.

Try the Ping Tool free at sadiqbd.com — check host reachability and measure response time instantly.