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No. It is impossible for this Java-based speed test to overestimate speed. It can, however, underestimate due to prevailing "Internet weather" between you and the test site (which is why, if you are most interested in your last mile speed, finding a nearby test site is important), but it can never overestimate.

If you try a few different test servers, including some of the third-party ones that also use our Java test applet, then the highest speed reported is closest to your last mile speed.

Don't forget that protocol overhead will mean that you never reach the actual speed advertised by your ISP. In some cases, especially PPPoE connections, you can lose almost 15% of advertised speed in protocol overhead.

In response to this problem, certain ISPs have set the actual sync rate of consumer broadband connections higher to provide a buffer against the overhead. The idea is a 15% up in advertised speed is worth less people calling into support and complain about lack of advertised throughput.

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edited by Mike See Profile
last modified: 2013-02-17 16:01:06