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Region Latency Estimate Calculator

Work out region latency estimate instantly with clear inputs, formula shown and shareable results.

About Region Latency Estimate Calculator

Light in fibre travels about 200,000 km per second, and real routes are typically 1.3 to 2 times the great-circle distance, so an 8,000 km separation gives roughly 120 ms round trip before any processing. Connection setup multiplies that: TLS 1.3 adds one round trip and TLS 1.2 two, so time to first byte on a cold connection is several times the RTT.

Formula

Region latency

fibre path = distance x inefficiency; one way = path / 200000 x 1000 ms; RTT = 2 x one way + processing; first byte = RTT x (1 + handshake round trips)

Worked example

With the default values below, Region Latency Estimate Calculator returns Estimated round-trip time of 132.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Distance between user and regionminimum 1 km
8,000 km
Route length versus great circleaccepts 1–3 x
1.5 x
Processing and queueing delayminimum 0 ms
12 ms
Round trips for connection setupaccepts 0–6
2

Results

Estimated round-trip time
132.0 ms
One-way propagation delay
60.0 ms
Time to first byte including connection setup
396.0 ms
Effective fibre path length
12,000 km

Step by step

  1. 1Values used
  2. 2Region latency
  3. 3Estimated round-trip time= 132.0 ms
  4. 4One-way propagation delay= 60.0 ms
  5. 5Time to first byte including connection setup= 396.0 ms
  6. 6Effective fibre path length= 12,000 km

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Can this latency be reduced?

Not the propagation component — it is physics. Only moving compute closer to users helps, which is what edge deployment and regional replicas exist to do.

How much does connection reuse help?

Enormously for repeat requests. Keep-alive removes the handshake round trips entirely, cutting time to first byte to a single RTT.

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