The Principle

The testing script will download a large file through your service provider. The download speed can be calculated while the duration is known after download completed. Also, the upload speed can be calculated by uploading large file. The system chooses the nearest server in your city so that the result would be a local internet speed. If you want to have a test on oversea internet speed, search a foreign city in the option menu. Then, select a server that located in that city to test again. To know more about the theory of bandwidth and delay, please read the following articales: End-to-end Delay and Optimizing Network Performance.