What is "slenderness ratio"

In architecture, the slenderness ratio, or simply slenderness is the quotient between the width of a building and its height.

Structural engineers generally consider slender those skyscrapers with a ratio minimum of 1:10 or 1:12. Slim towers require to adopt specific measures to counter the high strengths of the wind in the vertical cantilever, like including additional structure to endow greater rigidity to the building or diverse types of tuned mass dampers to avoid unwanted swinging.

The most slender residential skyscraper in the world is the Highcliff of Hong Kong which, with 72 floors and a height of , possesses one of the highest slenderness ratios,1:20. The extreme slenderness is something characteristic in Hong Kong, where there are more pencil-shaped buildings that in any other place in the world.