The EF Tornado Damage Scale 
The EF scale rates tornados by wind speed from EF-0 to EF-5.
At EF-0, wind speed is between 65 and 85 miles per hour, and the damage caused to buildings is light.
At EF-1, the speed is between 86 and 110 miles per hour, and damage is moderate. 
At EF-2, speed is between 111 and 135 miles per hour, and damage is considerable.
At EF-3, the wind moves at 136 to 165 miles per hour, and damage is severe.
In an EF-4 tornado, wind is between 166 and 200 miles per hour. The damage is classified as devastating.
The most dangerous tornado is an EF-5, where winds exceed 200 miles per hours. Damage is incredible.