Ping RTT to Distance Calculator
Turn a ping time into a maximum possible distance.
Your numbers
Your results
Maximum one-way distance (km)
Maximum one-way distance (km)
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In miles
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Propagation time one-way (ms)
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Rule of thumb: 1 ms RTT ≈ km of fibre
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Ping RTT to Distance Calculator by TheCalcTools
How the Ping RTT to Distance Calculator works
Subtract equipment delay from the RTT.
Halve it for one-way time.
Multiply by signal speed. Real fibre routes are longer than straight lines, so treat this as an upper bound on the straight-line distance.
The formula
Distance ≤ (RTT − processing) / 2 × v
Worked example
Using the default values shown in the calculator:
| Measured RTT (ms) | 40 |
|---|---|
| Processing and queuing allowance (ms) | 5 |
| Medium | Optical fibre (200,000 km/s) |
- (40 − 5) ms RTT leaves 35 ms; one way is 17.5 ms.
- At 200,000 km/s the signal covers at most 3,500 km (2,175 miles).
Result:
| Maximum one-way distance (km) | 3,500 |
|---|---|
| In miles | 2,175 |
| Propagation time one-way (ms) | 17.50 |
| Rule of thumb: 1 ms RTT ≈ km of fibre | 100 |
Frequently asked questions
Is the result the real distance?
No. Paths are rarely straight, so the real great-circle distance is usually shorter than the figure.
What is the rule of thumb?
About 100 km of fibre per 1 ms of RTT.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.