# London, UK → Sydney, Australia RTT

🇬🇧 **London, UK (LON)** → 🇦🇺 **Sydney, Australia (SYD)**

Measurement round: `2026-08-16T04:07:28Z`.

ICMP echo RTT from London, UK, to Sydney, Australia, averaged 258.1 ms in the 2026-08-16T04:07:28Z test round. Across 50 samples sent at 100 ms intervals, RTTs ranged from a minimum of 249.91 ms to a maximum of 280.95 ms, with 0% packet loss.

At a geodesic distance of 16,988.9 km, the theoretical vacuum round-trip floor is 113.34 ms and the fiber round-trip floor is 166.37 ms. The measured average is 1.55 times that fiber floor, a result consistent with a high-latency intercontinental route where absolute delay is dominated by the distance between the two endpoints.

This path ranked 19th among the 19 outbound routes measured in the same round. Its standard deviation was 6.66 ms and jitter was 5.27 ms; the 31.04 ms difference between maximum and minimum RTT is small relative to the 258.1 ms average, and the route set's median standard-deviation-to-average ratio of 3.28% points to broadly stable timing on this London-Sydney path.

## Latency Summary

| Metric               | Value                                                      |
| -------------------- | ---------------------------------------------------------- |
| RTT                  | **258.1 ms**                                               |
| Jitter               | **5.27 ms**                                                |
| Packet Loss          | **0%**                                                     |
| Standard Fiber Floor | **166.37 ms**                                              |
| Fiber Efficiency     | **64.5%**                                                  |
| Latency Tier         | High                                                       |
| Source Region        | [Europe](/docs/network/latency/regions/europe)             |
| Destination Region   | [Asia Pacific](/docs/network/latency/regions/asia-pacific) |

## Ping Measurement Series

The chart below renders the 50-sample ICMP echo measurement round for this route; an accessible table of every sample is included with the chart.

## Download This Route's Data

This route's measurement round is published as open data (CC BY 4.0) in CSV, JSON, and YAML. See [About This Measurement](#about-this-measurement) for citation guidance.

## Theoretical Fiber Latency

The public physical reference uses the GeoNames city centres for [London](https://www.geonames.org/2643743) (51.50853, -0.12574) and [Sydney](https://www.geonames.org/2147714) (-33.86785, 151.20732). It does not disclose either facility address.

| Physical Reference                            | Value           |
| --------------------------------------------- | --------------- |
| WGS-84 geodesic distance                      | **16,988.9 km** |
| Vacuum RTT floor                              | **113.34 ms**   |
| Standard fiber RTT floor ($n_g=1.4679$)       | **166.37 ms**   |
| Low-latency fiber material floor              | **165.7 ms**    |
| Engineering floor (5% path allowance)         | **174.71 ms**   |
| Research 1.33× mapped-fiber reference         | **221.27 ms**   |
| Estimated unamplified path loss               | **3567.7 dB**   |
| Transparent optical spans / inline amplifiers | **223 / 222**   |
| Published RTT inflation over fiber floor      | **1.55×**       |

Attenuation is used to estimate the number of 80 km optical spans; it does not directly slow light. See the full [theoretical fiber latency, GeoNames, attenuation, and amplifier methodology](/docs/network/latency/theoretical-fiber-latency).

## Stability & Trend

The current measurement round (2026-08-16T04:07:28Z) collected 50 ICMP echo samples on this route. Distribution statistics from that round:

| Round Statistic    | Value         |
| ------------------ | ------------- |
| Minimum RTT        | **249.91 ms** |
| Average RTT        | **258.1 ms**  |
| Maximum RTT        | **280.95 ms** |
| Standard deviation | **6.66 ms**   |
| Stdev / average    | **2.6%**      |

## Route Context

* Departure PoP: [London (LON)](/docs/network/latency/lon-london)
* Destination PoP: [Sydney (SYD)](/docs/network/latency/syd-sydney)
* Region overview: [Europe](/docs/network/latency/regions/europe) → [Asia Pacific](/docs/network/latency/regions/asia-pacific)
* Corridor overview: [Europe to Asia Pacific](/docs/network/latency/regions/europe-to-asia-pacific)
* Full global matrix: [Backbone Latency Matrix](/docs/network/latency)
* Physical methodology: [Theoretical Fiber Latency](/docs/network/latency/theoretical-fiber-latency)

## Related City-Pair Routes

**Reverse direction**

* [Sydney to London latency and RTT](/docs/network/latency/pairs/syd-lon-rtt) — 256.5 ms

**Fastest routes departing London (LON)**

* [London to Amsterdam latency and RTT](/docs/network/latency/pairs/lon-ams-rtt) — 5.2 ms
* [London to Paris latency and RTT](/docs/network/latency/pairs/lon-par-rtt) — 6.4 ms
* [London to Frankfurt latency and RTT](/docs/network/latency/pairs/lon-fra-rtt) — 13.6 ms
* [London to Berlin latency and RTT](/docs/network/latency/pairs/lon-ber-rtt) — 16.2 ms
* [London to Marseille latency and RTT](/docs/network/latency/pairs/lon-mrs-rtt) — 17.9 ms

**Fastest routes arriving at Sydney (SYD)**

* [Melbourne to Sydney latency and RTT](/docs/network/latency/pairs/mel-syd-rtt) — 9.8 ms
* [Singapore to Sydney latency and RTT](/docs/network/latency/pairs/sin-syd-rtt) — 94.5 ms
* [Tokyo to Sydney latency and RTT](/docs/network/latency/pairs/tyo-syd-rtt) — 101.9 ms
* [Taipei to Sydney latency and RTT](/docs/network/latency/pairs/tpe-syd-rtt) — 133.2 ms
* [Hong Kong to Sydney latency and RTT](/docs/network/latency/pairs/hkg-syd-rtt) — 137.2 ms

**Same corridor (Europe → Asia Pacific)**

* [Moscow to Hong Kong latency and RTT](/docs/network/latency/pairs/mow-hkg-rtt) — 118.6 ms
* [Moscow to Taipei latency and RTT](/docs/network/latency/pairs/mow-tpe-rtt) — 132.1 ms
* [Marseille to Singapore latency and RTT](/docs/network/latency/pairs/mrs-sin-rtt) — 139.6 ms

## About This Measurement

Published RTT reflects best-case backbone path behavior measured with ICMP echo probes between PoPs. End-user latency also depends on local access networks, congestion, routing policy, and traffic engineering. None of these values is an SLA.

The measurement round behind this page is published as open data under **CC BY 4.0** in the [Hats Network latency dataset](/opendata/latency/). Per-pair files are available at `/opendata/latency/latest/pairs/lon-syd.pings.{csv,json,yaml}`. When citing, include the route, the measurement round timestamp, and the dataset version — for example: "Hats Network latency dataset, London → Sydney round 2026-08-16T04:07:28Z, CC BY 4.0".

***

*Data auto-generated on August 16, 2026. Explore the [full interactive latency matrix](/docs/network/latency) or browse more [city-pair routes](/docs/network/latency/pairs).*

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## License and attribution

- **Canonical source:** [View the human-readable HTML page](https://hatsnet.io/docs/network/latency/pairs/lon-syd-rtt).
- **Original documentation:** © Hats Network Inc., licensed under [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/).
- **Public latency data:** © Hats Network Inc., licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).
- **Full terms:** [Content and Data License](https://hatsnet.io/docs/legal/content-and-data-license) — includes attribution requirements, third-party material, trademarks, source code and other exclusions.