West US · San Francisco Bay Area, California, US. How long a round trip from your machine to this region takes — and how much of that distance alone demands.
| Cloud | Microsoft Azure |
|---|---|
| Region code | westus |
| Region name | West US |
| Datacentre city | San Francisco Bay Area, California, US |
| Coordinates | 37.78, -122.42 |
| Published IPv4 prefixes | 1,440 |
| Probe endpoint | https://westus.livediagnostics.monitor.azure.com/ |
| Probe style | timed blind — the endpoint sends no CORS headers |
| Verification | Resolved to an address inside this region’s own published range, TCP 443 open. Checked 2026-08-21. |
Coordinates are the real datacentre city rather than the marketing region name, because they feed the distance maths below.
Light in fibre covers about 100 km per millisecond of round trip. These are the great-circle distances to San Francisco Bay Area, California and the latency no network can beat — not a measurement, a limit. What you actually measure is this plus routing.
| From | Distance | Floor |
|---|---|---|
| New York | 4,128 km | 41 ms |
| Los Angeles | 560 km | 5.6 ms |
| São Paulo | 10,434 km | 104 ms |
| London | 8,615 km | 86 ms |
| Frankfurt | 9,132 km | 91 ms |
| Johannesburg | 16,964 km | 170 ms |
| Dubai | 13,007 km | 130 ms |
| Mumbai | 13,493 km | 135 ms |
| Singapore | 13,582 km | 136 ms |
| Tokyo | 8,274 km | 83 ms |
| Sydney | 11,948 km | 119 ms |
Within 75 km of San Francisco Bay Area, California — near enough that distance sets no meaningful floor between them. When several sit in one city, the fastest is the city’s real floor; a slower neighbour is usually the endpoint’s own server time.
These figures are geometry. Your own round trip to westus depends on your connection and the route it takes — open the instrument, pick Azure, and sweep. Every region is timed from your browser against the endpoint listed above, and the result is split into the part physics demands and the part the network added.
See every Azure region on the Azure latency page.