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Ping to Distance Calculator

Convert a round-trip time into the furthest that server can possibly be.

What you provide

Time spent in routers and at the far end rather than travelling. Leave at 0 for the absolute ceiling.

How much longer the fibre path is than the straight line. Terrestrial routes are typically 1.4 to 2.

Result

20 ms is at most about 1,339,073 km away

Physics sets a hard floor on latency that no amount of bandwidth changes. Light in fibre covers roughly 200 km per millisecond, and cable never runs in a straight line, so a realistic figure is 100 to 150 km of geography per millisecond of round trip. This is why a server across an ocean cannot answer in 5 ms however it is provisioned, and why a claimed location that would need faster-than-light propagation is simply wrong. Read the result as a ceiling rather than an estimate: real round trips include queueing, forwarding and the far end taking time to reply, all of which add milliseconds that have nothing to do with distance.

Diagnostic telemetry
Round-trip time
20 ms
Fibre path lengthCable distance, at two-thirds the speed of light
2,008,609 km
Straight-line distanceAssuming the cable runs 1.5× the direct path
1,339,073 km
Absolute ceiling in vacuumNo signal of any kind can have travelled further
2,997,925 km
Earth circumference for scaleHalf of it, 20,038 km, is the furthest two points can be apart
40,075 km

What this cannot tell you

  • This is physics applied to a number you type in. It does not ping anything and cannot locate a server.
  • The answer is an upper bound, not a position. Real latency includes queueing and processing that add milliseconds unrelated to distance, so the true distance is always less than the ceiling shown.

Take this with you

How this calculation works

Light in single-mode fibre travels at roughly two-thirds of its speed in vacuum, which works out to about 200 km per millisecond. A round trip covers the distance twice, so the one-way path length is half the propagation time multiplied by that speed. Cable never runs in a straight line, so a route factor converts the fibre path into a plausible geographic distance. The vacuum figure is shown as well, because nothing of any kind can have travelled further than that in the time available.

What the results mean

Fibre path length
How much cable the signal covered, assuming the whole round trip was spent travelling. Always an overestimate, since some of it was spent in equipment.
Straight-line distance
The fibre path divided by your route factor. This is the figure to compare against a map.
Absolute ceiling in vacuum
The hard physical limit. A claimed location further away than this cannot be where the traffic is being answered.

Common problems and fixes

A VPN claims a country the latency cannot support
Compare the ceiling against the distance on a map. If a server claims to be in Sydney and answers from Europe in 30 ms, that is roughly 4,500 km at best against a real distance over 16,000 km, so the exit is not where it says. Providers commonly locate servers in one place and register the addresses to another, which is why geolocation databases and physics often disagree.
The distance seems far too short for a known location
You are probably reaching a CDN edge rather than the origin. Most large sites answer from the nearest point of presence, so a ping to a well-known domain measures the distance to a cache a few kilometres away, not to the company headquarters. Trace the route to see where the traffic actually terminates.

Frequently asked questions

How far is one millisecond?

About 200 km of fibre one way, or 100 km of round trip. Once cable routing is allowed for, a practical rule is 100 to 150 km of geography per millisecond of round-trip time. Anything better than that is not possible, and most real paths are worse.

Why is my latency higher than the distance suggests?

Because distance is only one component. Every router adds queueing and forwarding delay, the last mile technology contributes its own fixed cost, and the server takes time to respond. Cable and DSL add a few milliseconds, mobile networks considerably more, and satellite is dominated by the altitude of the satellite rather than by ground distance.

Does bandwidth reduce latency?

Not the propagation part, which is fixed by physics. More bandwidth reduces the time to put a large object on the wire and reduces queueing when a link is congested, so it helps with transfer time. The floor set by distance does not move.

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