The Fujita Scale of tornado intensity

F-Scale

value wind speed range*

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description of damage

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photograph

of typical damage

metres

per second

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feet

per second

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kilometres

per hour miles

per hour

F0 18 - 32 metres/sec

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64 - 116 km/hr 59 - 106 feet/sec

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40 - 72 mph light chimneys and billboards damaged; branches broken; shallow-rooted trees pushed over

F1 32 - 50 metres/sec

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117 - 181 km/hr 106 - 165 feet/sec

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73 - 112 mph moderate the beginning of hurricane-force wind speed**; surfaces peeled off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the road

F2 50 - 70 metres/sec

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182 - 253 km/hr 165 - 231 feet/sec

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113 - 157 mph considerable roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light-object missiles generated

F3 70 - 92 metres/sec

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254 - 332 km/hr 231 - 303 feet/sec

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158 - 206 mph severe roofs and some walls torn off well-constructed houses; trains overturned; most trees in forests uprooted; heavy cars lifted off ground and thrown

F4 92 - 116 metres/sec

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333 - 418 km/hr 303 - 382 feet/sec

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207 - 260 mph devastating well-constructed houses leveled; structures with weak foundations blown some distance; cars thrown; large-object missiles generated

F5 116 - 142 metres/sec

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419 - 512 km/hr 382 - 466 feet/sec

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261 - 318 mph incredible strong frame houses lifted off foundations and carried considerable distance to disintegration; automobile-sized missiles flung through the air farther than 100 metres (330 feet); trees debarked; incredible phenomena occur

*Wind speed ranges were defined by Fujita to be "the fastest 1/4-mile wind speed." For an F3 wind speed of 320 km/hr (200 mph), the duration of the maximum wind at a point would thus be about four seconds.

**Beaufort Force 8 corresponds to a wind speed just slightly higher than the start of F0; Beaufort Force 12 (the minimum wind speed required for a tropical storm to be declared a hurricane) corresponds to the start of F1.

Sources: Modified from Fujita, T. Theodore, "Proposed Characterization of Tornadoes and Hurricanes by Area and Intensity," Satellite and Mesometeorology Research Project Research Paper 91, Department of the Geophysical Sciences, University of Chicago, 44 pp. (1971); and Fujita, T. Theodore, "Experimental Classification of Tornadoes in FPP Scale," Satellite and Mesometeorology Research Project Research Paper 98, Department of the Geophysical Sciences, University of Chicago, 15 pp. (1973).