Relates tornado intensity indirectly to structural and/or vegetative damage. The estimated wind speed is calculated using the following formula: V = 6. 30 (F+2)1. 5 m s−1. A six-point scale has been developed that corresponds to the following wind-speed estimates:

F0 (light damage): 18–32 m s−1

F1 (moderate damage): 33–49 m s−1

F2 (considerable damage): 50–69 m s−1

F3 (severe damage): 70–92 m s−1

F4 (devastating damage): 93–116 m s−1

F5 (incredible damage):117–142 m s−1. Although extremely dependent on the design of a structure and the tree type, the following visual characteristics of the damage have been assigned to the F-scale. F0 - Some damage to chimneys; branches broken; shallow-rooted trees knocked over. F1 - Surface of roofs peeled off; mobile homes pushed off foundations or overturned; moving autos pushed off road. F2 - Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted. F3 - Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off ground and thrown. F4 - Well-constructed houses leveled; structures with weak foundations blown off; large missiles generated. F5 - Strong frame houses lifted off foundations and carried considerable distances; automobile- sized missiles flying through the air for distances in excess of 100 m; trees debarked.