Your Wi-Fi speed can slow down due to many factors, including your distance from an access point, the number of networks in the area and even interference from a microwave. To test your speed, visit a site that pings a local server from your IP address to get accurate download and upload rates for your connection.
Different access points transmit Wi-Fi using different technologies, so you can't use a single formula to calculate falloff. However, even a router with the newest technology provides a weak signal at the perimeter of its range, so moving as close to the source as possible eliminates slowdown from low signal strength. A running microwave oven emits radiation at around 2.4 GHz, a common router setting, and public places such as office buildings can host hundreds of networks that contribute to muddy signals with noticeable Wi-Fi slowdown.
Ping a Nearby Server
Visit a website such as Speedtest, TestMySpeed or Pingtest to ping a local server and immediately receive test results. Click "Begin Test" to ping the nearest server and test your download and upload rates. These tests work by transmitting a signal from your network to the server and measuring the response's latency, similar to the way a radio ping test measures the latency of a signal's bounce off a landmark or building. You receive results in units of megabits per second, making those results easy to compare to your Internet service provider's specifications.