The Enhanced Fujita Scale (EF Scale) — Tornado Ratings Explained

What does each EF rating mean?

The full scale, with estimated 3-second peak gust ranges:

• EF0 — 65 to 85 mph. Light damage: shingles peeled, branches broken, billboards damaged. Most tornadoes are EF0.
• EF1 — 86 to 110 mph. Moderate damage: roofs stripped, mobile homes overturned, exterior walls displaced.
• EF2 — 111 to 135 mph. Considerable damage: roofs torn off well-built houses, mobile homes destroyed, large trees uprooted.
• EF3 — 136 to 165 mph. Severe damage: well-built houses lose entire stories, trains overturned. NWS classifies EF2–EF3 as "strong" and reserves "violent" for EF4–EF5.
• EF4 — 166 to 200 mph. Devastating damage: well-built houses leveled, cars thrown long distances.
• EF5 — over 200 mph. Incredible damage: well-built houses swept off foundations, cars thrown over a kilometer, asphalt scoured. Average of about 1 EF5 per year, sometimes zero in a year.

Why was the original Fujita scale replaced?

Ted Fujita's original scale (1971) used estimated wind speeds tied to damage descriptions. Two problems emerged over decades of use: the wind-speed bins were too high — F5 was 261-318 mph, which engineering studies later showed was beyond what was actually needed to cause F5 damage — and the damage descriptions were vague and applied unevenly across surveyors and regions.

The Enhanced Fujita scale, developed by a Texas Tech University-led team and adopted by NWS on February 1, 2007, fixed both. It introduced 28 specific Damage Indicators (DIs) — like "one- or two-family residence," "free-standing pole barn," "transmission tower" — each with 8 to 12 Degrees of Damage (DoDs) and engineering-derived wind-speed estimates. Surveys now match observed damage to a DI/DoD combination and read off the wind speed.

This means a 1999 F5 and a 2013 EF5 are not directly comparable on wind speed. The damage threshold is similar, but the EF wind speeds are about 30-50 mph lower than the equivalent F-rating wind speeds.

How is an EF rating assigned?

NWS damage-survey teams arrive at the tornado's path within 24-72 hours. They walk or drive the path, photograph and GPS-tag damage points, and at each point identify the most-damaged structure that matches one of the 28 DIs. They assign that DI a Degree of Damage (typically 1-10), which produces an "expected" wind speed plus an upper and lower bound.

The tornado's official rating is the highest wind speed (and corresponding EF tier) found along the entire path, even if it occurred only at one point. So a tornado that scored EF1 over 99% of its track but EF4 in one neighborhood is rated EF4. This is why ratings sometimes feel disproportionate to a particular town's experience.

If no engineered structures are along the path (rural farmland, open prairie), the survey team can use trees, terrain, or vehicle-throwing distances as proxies, but the rating ceiling is typically EF3 because EF4/EF5 require well-built structures to assess.

What's the difference between EF and F?

The original Fujita scale (F0-F5) was used in the US from 1971 to January 31, 2007. The Enhanced Fujita scale (EF0-EF5) replaced it on February 1, 2007 and is used today.

VORTEX's tornado-history pages use whichever rating system was in effect at the time of the event. So a 1974 tornado will appear as F4 or F5; a 2024 tornado will appear as EF4 or EF5. We group them together for counting purposes (an F3 and an EF3 are similar in damage threshold) but show the original rating string so the historical record stays accurate.

You should never write "EF5" for a pre-2007 tornado. The 1999 Moore tornado is F5, not EF5. The 1974 Xenia tornado is F5. This is a common mistake in news articles and even research papers.

How does the EF scale handle multi-vortex tornadoes?

Multi-vortex tornadoes can produce sub-vortex wind speeds over 300 mph (measured by mobile Doppler radar in 1999 Bridge Creek-Moore and 2013 El Reno). Those measurements would imply an "EF6" rating, but the EF scale tops out at EF5 because no observed damage requires winds above ~200 mph to explain. Asphalt scouring, vehicle-throwing distances, and foundation sweeping all match EF5 wind estimates with significant margin.

The EF scale is a damage scale, not a wind scale. So while sub-vortex winds may exceed 300 mph, the damage they leave is rated EF5 because that's what the engineering says is required. Some meteorologists advocate for a research-grade scale that incorporates Doppler measurements directly. No such scale is currently in operational use.

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