Nc 3700

Welcome to the world of marketing.  Consider the fact that automobile manufacturers advertise brake horsepower (the power delivered at an engine's output shaft) instead of wheel horsepower (the actual power delivered to the wheels after losses incurred by the drivetrain and attached equipment).  Wheel horsepower provides a truer measure of an automobile's performance, but it is never advertised because it is always lower than brake horsepower.  When it comes to advertising, bigger is better, right? :smileywink:

Advertised Wi-Fi speeds are just like brake horsepower.  Actual Wi-Fi speeds (i.e. the rate of bits actually delivered to your device) are much lower after losses.  These include, just to name a couple of examples, absorption by walls and radio interference.  There are many, many other factors that I won't go into here.  I describe a few more factors that affect Wi-Fi speed here (link).  A very crude rule of thumb is to take the advertised speed and cut it in half to get a best-case estimate of the actual Wi-Fi speed.  

But you may be wondering, why do advertised Wi-Fi speeds differ so much from Internet speeds?  "Losses" from wired connections are very different and generally much less than wireless connections.  But another reason is simply, "You are lucky."  Many people never get the advertised Internet speeds due to something called oversubscription (link).  Marketing applies to Internet service, too.