Your approximate location comes from the measurement endpoint's own response — no browser location permission is requested. The nearest candidates are then raced with several small requests each, and the one with the lowest stable round-trip time wins. Network distance decides, not map distance.
A short probe sizes the real run, then several transfers run in parallel for a fixed window — one connection rarely saturates a fast link. Every request is unique and uncached, the opening ramp-up is excluded, and the run is cut off on time rather than waiting for a large file to finish.
Test traffic goes directly between your browser and the public measurement endpoint. Results are not sent to us, not stored, and not associated with you — they exist only in this tab until you close it.
A browser result is a measurement of this device, on this connection, at this moment — Wi-Fi, the device itself and whatever else is using the line all affect it. For a wired test of the circuit itself, or if the number is persistently below what you pay for, talk to our team.