F-Scale Number

Intensity Phrase

Wind Speed

Type of Damage Done

F0

Gale tornado

40-72 mph

Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards.

F1

Moderate tornado

73-112 mph

The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads; attached garages may be destroyed.

F2

Significant tornado

113-157 mph

Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated.

F3

Severe tornado

158-206 mph

Roof and some walls torn off well constructed houses; trains overturned; most trees in forest uprooted

F4

Devastating tornado

207-260 mph

Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.

F5

Incredible tornado

261-318 mph

Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; steel reinforced concrete structures badly damaged.