# Ashburn, USA → Tokyo, Japan RTT

🇺🇸 **Ashburn, USA (IAD)** → 🇯🇵 **Tokyo, Japan (TYO)**

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

The 2026-08-16T04:07:28Z round of ICMP echo measurements from Ashburn, USA to Tokyo, Japan collected 50 samples at 100 ms intervals, yielding an average RTT of 141.9 ms, a minimum of 136.1 ms and a maximum of 154.55 ms, with zero packet loss.

On the 19-route set, this path ranked 13th, and its variability ratio of roughly 3.0 percent sits below the network-wide median of 3.28 percent. A standard deviation of 4.32 ms and jitter of 3.99 ms confirm a stable trans-Pacific latency profile despite the route's mid-pack ranking.

The 10,894.6 km great-circle distance places the theoretical vacuum floor at 72.68 ms and the practical fiber floor at 106.69 ms. The measured 141.9 ms average is 1.33 times the fiber floor, or about 75.2 percent fiber efficiency, leaving a moderate but consistent gap between observed RTT and the physical lower bound.

## Latency Summary

| Metric               | Value                                                        |
| -------------------- | ------------------------------------------------------------ |
| RTT                  | **141.9 ms**                                                 |
| Jitter               | **3.99 ms**                                                  |
| Packet Loss          | **0%**                                                       |
| Standard Fiber Floor | **106.69 ms**                                                |
| Fiber Efficiency     | **75.2%**                                                    |
| Latency Tier         | Good                                                         |
| Source Region        | [North America](/docs/network/latency/regions/north-america) |
| 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 [Ashburn](https://www.geonames.org/4744870) (39.04372, -77.48749) and [Tokyo](https://www.geonames.org/1850147) (35.68950, 139.69171). It does not disclose either facility address.

| Physical Reference                            | Value           |
| --------------------------------------------- | --------------- |
| WGS-84 geodesic distance                      | **10,894.6 km** |
| Vacuum RTT floor                              | **72.68 ms**    |
| Standard fiber RTT floor ($n_g=1.4679$)       | **106.69 ms**   |
| Low-latency fiber material floor              | **106.26 ms**   |
| Engineering floor (5% path allowance)         | **112.04 ms**   |
| Research 1.33× mapped-fiber reference         | **141.9 ms**    |
| Estimated unamplified path loss               | **2287.9 dB**   |
| Transparent optical spans / inline amplifiers | **143 / 142**   |
| Published RTT inflation over fiber floor      | **1.33×**       |

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        | **136.1 ms**  |
| Average RTT        | **141.9 ms**  |
| Maximum RTT        | **154.55 ms** |
| Standard deviation | **4.32 ms**   |
| Stdev / average    | **3.0%**      |

## Route Context

* Departure PoP: [Ashburn (IAD)](/docs/network/latency/iad-ashburn)
* Destination PoP: [Tokyo (TYO)](/docs/network/latency/tyo-tokyo)
* Region overview: [North America](/docs/network/latency/regions/north-america) → [Asia Pacific](/docs/network/latency/regions/asia-pacific)
* Corridor overview: [North America to Asia Pacific](/docs/network/latency/regions/north-america-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**

* [Tokyo to Ashburn latency and RTT](/docs/network/latency/pairs/tyo-iad-rtt) — 142.9 ms

**Fastest routes departing Ashburn (IAD)**

* [Ashburn to New York latency and RTT](/docs/network/latency/pairs/iad-nyc-rtt) — 6 ms
* [Ashburn to Miami latency and RTT](/docs/network/latency/pairs/iad-mia-rtt) — 27.4 ms
* [Ashburn to Los Angeles latency and RTT](/docs/network/latency/pairs/iad-lax-rtt) — 60.7 ms
* [Ashburn to Seattle latency and RTT](/docs/network/latency/pairs/iad-sea-rtt) — 62.3 ms
* [Ashburn to London latency and RTT](/docs/network/latency/pairs/iad-lon-rtt) — 70.3 ms

**Fastest routes arriving at Tokyo (TYO)**

* [Taipei to Tokyo latency and RTT](/docs/network/latency/pairs/tpe-tyo-rtt) — 31.9 ms
* [Hong Kong to Tokyo latency and RTT](/docs/network/latency/pairs/hkg-tyo-rtt) — 44.9 ms
* [Singapore to Tokyo latency and RTT](/docs/network/latency/pairs/sin-tyo-rtt) — 68.9 ms
* [Seattle to Tokyo latency and RTT](/docs/network/latency/pairs/sea-tyo-rtt) — 85 ms
* [Los Angeles to Tokyo latency and RTT](/docs/network/latency/pairs/lax-tyo-rtt) — 101.2 ms

**Same corridor (North America → Asia Pacific)**

* [Seattle to Taipei latency and RTT](/docs/network/latency/pairs/sea-tpe-rtt) — 114.7 ms
* [Seattle to Hong Kong latency and RTT](/docs/network/latency/pairs/sea-hkg-rtt) — 130.4 ms
* [Los Angeles to Taipei latency and RTT](/docs/network/latency/pairs/lax-tpe-rtt) — 132.9 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/iad-tyo.pings.{csv,json,yaml}`. When citing, include the route, the measurement round timestamp, and the dataset version — for example: "Hats Network latency dataset, Ashburn → Tokyo 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/iad-tyo-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.