What is [on average] the top speed you can reach whilst doing a fast walk? i'm looking for a treadmill on....?

Question

ebay, and i need to know what is the minimum speed of treadmill that i can buy that will be sufficient for a fast walk....some are listed at 4mph/6kph but i'm not sure if thats fast enough....i always thought a comfortable walking speed was 4mph, so i need something twice that speed.

Answer 1

I'd go with about 6 MPH, after that, you are RUNNING.

Answer 2

4 mph is around a light jog, 5 mph is a fast jog, and 6+ is a run.  

Answer 3

20mph