# Tokyo, Japan → Seattle, USA RTT

🇯🇵 **Tokyo, Japan (TYO)** → 🇺🇸 **Seattle, USA (SEA)**

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

For the 2026-08-16T04:07:28Z round, ICMP echo probes from Tokyo to Seattle averaged 84.8 ms, with a minimum of 81.06 ms and a maximum of 94.31 ms. All 50 probes succeeded, yielding 0% packet loss and 2.73 ms jitter.

Among the 19 routes from Tokyo measured in this round, Seattle placed 4th in average latency, putting it in the faster group. Its spread-to-average ratio was about 3.5%, above the 3.28% median for the same set, so raw speed came with slightly wider relative variation than the typical Tokyo-origin path.

Tokyo and Seattle are both trans-Pacific interconnection points, and the 7,715.2 km great-circle distance gives a vacuum floor of 51.47 ms and a fiber floor of 75.55 ms. At 84.8 ms, the average RTT is only 1.12 times that fiber floor, an efficiency of 89.1%, showing the route stays close to its physical distance floor.

## Latency Summary

| Metric               | Value                                                        |
| -------------------- | ------------------------------------------------------------ |
| RTT                  | **84.8 ms**                                                  |
| Jitter               | **2.73 ms**                                                  |
| Packet Loss          | **0%**                                                       |
| Standard Fiber Floor | **75.55 ms**                                                 |
| Fiber Efficiency     | **89.1%**                                                    |
| Latency Tier         | Good                                                         |
| Source Region        | [Asia Pacific](/docs/network/latency/regions/asia-pacific)   |
| Destination Region   | [North America](/docs/network/latency/regions/north-america) |

## 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 [Tokyo](https://www.geonames.org/1850147) (35.68950, 139.69171) and [Seattle](https://www.geonames.org/5809844) (47.60621, -122.33207). It does not disclose either facility address.

| Physical Reference                            | Value          |
| --------------------------------------------- | -------------- |
| WGS-84 geodesic distance                      | **7,715.2 km** |
| Vacuum RTT floor                              | **51.47 ms**   |
| Standard fiber RTT floor ($n_g=1.4679$)       | **75.55 ms**   |
| Low-latency fiber material floor              | **75.25 ms**   |
| Engineering floor (5% path allowance)         | **79.34 ms**   |
| Research 1.33× mapped-fiber reference         | **100.49 ms**  |
| Estimated unamplified path loss               | **1620.2 dB**  |
| Transparent optical spans / inline amplifiers | **102 / 101**  |
| Published RTT inflation over fiber floor      | **1.12×**      |

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        | **81.06 ms** |
| Average RTT        | **84.8 ms**  |
| Maximum RTT        | **94.31 ms** |
| Standard deviation | **2.93 ms**  |
| Stdev / average    | **3.5%**     |

## Route Context

* Departure PoP: [Tokyo (TYO)](/docs/network/latency/tyo-tokyo)
* Destination PoP: [Seattle (SEA)](/docs/network/latency/sea-seattle)
* Region overview: [Asia Pacific](/docs/network/latency/regions/asia-pacific) → [North America](/docs/network/latency/regions/north-america)
* 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**

* [Seattle to Tokyo latency and RTT](/docs/network/latency/pairs/sea-tyo-rtt) — 85 ms

**Fastest routes departing Tokyo (TYO)**

* [Tokyo to Taipei latency and RTT](/docs/network/latency/pairs/tyo-tpe-rtt) — 32.3 ms
* [Tokyo to Hong Kong latency and RTT](/docs/network/latency/pairs/tyo-hkg-rtt) — 44.8 ms
* [Tokyo to Singapore latency and RTT](/docs/network/latency/pairs/tyo-sin-rtt) — 69.4 ms
* [Tokyo to Los Angeles latency and RTT](/docs/network/latency/pairs/tyo-lax-rtt) — 101.2 ms
* [Tokyo to Sydney latency and RTT](/docs/network/latency/pairs/tyo-syd-rtt) — 101.9 ms

**Fastest routes arriving at Seattle (SEA)**

* [Los Angeles to Seattle latency and RTT](/docs/network/latency/pairs/lax-sea-rtt) — 26.9 ms
* [New York to Seattle latency and RTT](/docs/network/latency/pairs/nyc-sea-rtt) — 58.7 ms
* [Ashburn to Seattle latency and RTT](/docs/network/latency/pairs/iad-sea-rtt) — 62.3 ms
* [Miami to Seattle latency and RTT](/docs/network/latency/pairs/mia-sea-rtt) — 81.9 ms
* [Taipei to Seattle latency and RTT](/docs/network/latency/pairs/tpe-sea-rtt) — 115.8 ms

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

* [Hong Kong to Seattle latency and RTT](/docs/network/latency/pairs/hkg-sea-rtt) — 131.6 ms
* [Taipei to Los Angeles latency and RTT](/docs/network/latency/pairs/tpe-lax-rtt) — 132 ms
* [Sydney to Los Angeles latency and RTT](/docs/network/latency/pairs/syd-lax-rtt) — 136.5 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/tyo-sea.pings.{csv,json,yaml}`. When citing, include the route, the measurement round timestamp, and the dataset version — for example: "Hats Network latency dataset, Tokyo → Seattle 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/tyo-sea-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.