Fujita scale The Fujita scale (F-scale) uses actual damage to determine a tornado’s wind speed:

F0 Gale Tornado 40-72 mph Some damage to chimneys. Tree branches broken off. Shallow rooted trees uprooted.
F1 Moderate Tornado 73-112 mph Peels surface off roofs. Mobile homes overturned. Moving autos pushed off roads.
F2 Significant Tornado 113-157 mph Considerable damage. Roofs torn off frame houses. Large trees snapped or uprooted. Light-object missiles generated.
F3 Severe Tornado 158-206 mph Severe damage. Roofs and some walls torn off well constructed homes. Trains overturned. Most trees in forests uprooted. Heavy cars lifted off ground.
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 disintegrated. Automobile-sized missiles fly through the air in excess of 100 mph. Trees debarked.