# Frankfurt, Germany → London, UK RTT

🇩🇪 **Frankfurt, Germany (FRA)** → 🇬🇧 **London, UK (LON)**

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

ICMP echo RTT measurements from Frankfurt to London in round 2026-08-16T04:07:28Z averaged 12.9 ms over 50 samples, with a minimum of 12.38 ms, a maximum of 14.46 ms, and 0% packet loss.

Given a geodesic distance of 639.5 km, the vacuum floor is 4.27 ms and the fiber floor is 6.26 ms. The measured RTT is 2.06 times the fiber floor, or 48.5% fiber efficiency, showing that this cross-border route carries more overhead above the optical straight-line bound than the tightest possible path.

Within a route set of 19 measured paths, this route ranked fourth, while the network median variability was 3.28% of average RTT. Here the standard deviation was 0.43 ms and jitter was 0.33 ms, approximately 3.3% of the mean, placing stability near the network median.

Zero packet loss and ultra-low tier latency still make this a consistent reference for Frankfurt–London RTT, though the lower fiber efficiency hints at more headroom for path optimization than the raw distance alone implies.

## Latency Summary

| Metric               | Value                                          |
| -------------------- | ---------------------------------------------- |
| RTT                  | **12.9 ms**                                    |
| Jitter               | **0.33 ms**                                    |
| Packet Loss          | **0%**                                         |
| Standard Fiber Floor | **6.26 ms**                                    |
| Fiber Efficiency     | **48.5%**                                      |
| Latency Tier         | Ultra-Low                                      |
| Source Region        | [Europe](/docs/network/latency/regions/europe) |
| Destination Region   | [Europe](/docs/network/latency/regions/europe) |

## 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 [Frankfurt am Main](https://www.geonames.org/2925533) (50.11552, 8.68417) and [London](https://www.geonames.org/2643743) (51.50853, -0.12574). It does not disclose either facility address.

| Physical Reference                            | Value        |
| --------------------------------------------- | ------------ |
| WGS-84 geodesic distance                      | **639.5 km** |
| Vacuum RTT floor                              | **4.27 ms**  |
| Standard fiber RTT floor ($n_g=1.4679$)       | **6.26 ms**  |
| Low-latency fiber material floor              | **6.24 ms**  |
| Engineering floor (5% path allowance)         | **6.58 ms**  |
| Research 1.33× mapped-fiber reference         | **8.33 ms**  |
| Estimated unamplified path loss               | **134.3 dB** |
| Transparent optical spans / inline amplifiers | **9 / 8**    |
| Published RTT inflation over fiber floor      | **2.06×**    |

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        | **12.38 ms** |
| Average RTT        | **12.9 ms**  |
| Maximum RTT        | **14.46 ms** |
| Standard deviation | **0.43 ms**  |
| Stdev / average    | **3.3%**     |

## Route Context

* Departure PoP: [Frankfurt (FRA)](/docs/network/latency/fra-frankfurt)
* Destination PoP: [London (LON)](/docs/network/latency/lon-london)
* Region overview: [Europe](/docs/network/latency/regions/europe) → [Europe](/docs/network/latency/regions/europe)
* 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**

* [London to Frankfurt latency and RTT](/docs/network/latency/pairs/lon-fra-rtt) — 13.6 ms

**Fastest routes departing Frankfurt (FRA)**

* [Frankfurt to Amsterdam latency and RTT](/docs/network/latency/pairs/fra-ams-rtt) — 5.9 ms
* [Frankfurt to Berlin latency and RTT](/docs/network/latency/pairs/fra-ber-rtt) — 6.1 ms
* [Frankfurt to Paris latency and RTT](/docs/network/latency/pairs/fra-par-rtt) — 7.6 ms
* [Frankfurt to Marseille latency and RTT](/docs/network/latency/pairs/fra-mrs-rtt) — 16.4 ms
* [Frankfurt to Moscow latency and RTT](/docs/network/latency/pairs/fra-mow-rtt) — 34.7 ms

**Fastest routes arriving at London (LON)**

* [Amsterdam to London latency and RTT](/docs/network/latency/pairs/ams-lon-rtt) — 5.2 ms
* [Paris to London latency and RTT](/docs/network/latency/pairs/par-lon-rtt) — 6.4 ms
* [Berlin to London latency and RTT](/docs/network/latency/pairs/ber-lon-rtt) — 15.2 ms
* [Marseille to London latency and RTT](/docs/network/latency/pairs/mrs-lon-rtt) — 18.9 ms
* [Moscow to London latency and RTT](/docs/network/latency/pairs/mow-lon-rtt) — 42.4 ms

**Same corridor (Europe → Europe)**

* [London to Amsterdam latency and RTT](/docs/network/latency/pairs/lon-ams-rtt) — 5.2 ms
* [Amsterdam to Frankfurt latency and RTT](/docs/network/latency/pairs/ams-fra-rtt) — 5.9 ms
* [Berlin to Frankfurt latency and RTT](/docs/network/latency/pairs/ber-fra-rtt) — 6.1 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/fra-lon.pings.{csv,json,yaml}`. When citing, include the route, the measurement round timestamp, and the dataset version — for example: "Hats Network latency dataset, Frankfurt → London 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/fra-lon-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.