A tremendous amount. F5 tornadoes are absolutely devastating events. When they strike towns damage costs can go into the hundreds of millions of dollars with thousands of homes destroyed. Several tornadoes have even caused damage upwards of $1 billion.
A F6 tornado does not exist on the Enhanced Fujita scale, which ranges from F0 to F5. The most powerful tornado category, an F5 tornado, has wind speeds exceeding 200 mph and can cause catastrophic damage.
In most cases an F5 tornado will be larger than an F1. However, tornado ratings are a measure of the strength of a tornado, not its size. F5 is the strongest category, and such tornadoes are usually very large, but a few have been fairly small. Conversely, F1 is the second lowest rating (F0 is the lowest) and such tornadoes are generally small, but some have been huge.
F5 is the strongest category of tornado which rates tornadoes from F0 to F5 based on damage. An F5 tornado can sweep a house clean off its foundation.
F5 damage is characterized as incredible. F5 damage includes well constructed houses being torn clean from their foundations and steel reinforced concrete structures suffering heavy damage. Skyscrapers will suffer "significant structural deformation."
Much more. Typical F1 damage includes badly damage roofs, trailers overturned or partially destroyed, broken windows and collapsed porches. F1 tornadoes often cause damage in the tens or hundreds of thousands of dollars, occasionally in the millions. Typical F5 damage includes well constructed houses wiped clean off their foundations and reinforced concrete structures heavily damaged. They can even peel asphalt from roads. F5 tornadoes often cause damage in the tens or hundreds of millions of dollars. A few have even caused over $1 billion in damage.
It is not so much the biggest but the strongest tornadoes that are rated F5. The Fujita scale rates tornadoes from F0 to F5 based on how severe their damage is. F5 damage is the worst, it is complete destruction. F5 tornadoes tend to be very large, but aren't always. Size is not a factor in assessing tornado strength.
F5 tornadoes cause total devastation. Well constructed houses are wiped clean off their foundations and steel reinforced concrete structures are heavily damaged. In addtion, many F5 tornadoes are quite large, so major damage can cover entire neighborhoods.
An F5 tornado does not form directly from an F1 tornado. Tornado intensity is determined by the Enhanced Fujita Scale based on wind speeds and damage. It is possible for a tornado to rapidly intensify due to various atmospheric conditions, leading to an increase in intensity from an F1 to an F5 tornado.
Generally yes, by the wind estimates of the original Fujita scale winds over 260 mph are in the F5 range. However if such a tornado goes across open country and so does not cause F5 damage it would likely be given a lower rating.
Amazingly, there were no deaths in the Elie tornado, which is unusual for an F5. The one house which suffered F5 damage was unoccupied at the time it was struck.
The severity of the damage. It is a common misconception that it measure wind speed, but in truth, wind speed estimated based on the damage.
There are theoretical categories beyond F5 but none of theme have ever been used. Since F5 damage is total destruction there is no real way of rating a tornado higher than F5. Also, a tornado's rating is not dependent on its size. So a bigger tornado does not necessarily get a higher rating.