Basic Definition A high-rise building is defined as a building 35 meters or greater in height, which is divided at regular intervals into occupiable levels. To be considered a high-rise building an edifice must be based on solid ground, and fabricated along its full height through deliberate processes (as opposed to naturally-occurring formations). [Enlarge] General Definition A high-rise building is distinguished from other tall man-made structures by the following guidelines: It must be divided into multiple levels of at least 2 meters height; If it has fewer than 12 such internal levels, then the highest undivided portion must not exceed 50% of the total height; Indistinct divisions of levels such as stairways shall not be considered floors for purposes of eligibility in this definition. Any method of structural support which is consistent with this definition is allowable, whether masonry, concrete, or metal frame. In the few cases where such a building is not structurally self-supporting (e.g. resting on a slope or braced against a cliff), it may still be considered a high-rise building but is not eligible for any height records unless the record stipulates inclusions of this type. Minimum Height The cutoff between high-rise and low-rise buildings is 35 meters. This height was chosen based on an original 12-floor cutoff, used for the following reasons: 1) Twelve floors is normally the minimum height needed to achieve the physical presence which earns the name "high-rise"; 2) The twelve-floor limit represents a compromise between ambition and manageability for a worldwide database. Since height information on smaller buildings is usually not readily available, the twelve-floor limit is still used in most areas covered by the websites belonging to the Emporis Network. A building of fewer floors may only be included as a high-rise when its exact height is known. In most cases, a city is considered to have a satisfactory listing of high-rise buildings when all twelve-floor buildings are counted. Single vs. Multiple Building In most cases there is no trouble deciding what constitutes a separate building. Only when they are linked in unusual ways is there a logical difficulty. The following rules have been adopted by the EDC to set a uniform standard: Any two towers which are separated for at least 2/3 of each tower's height are considered separate buildings UNLESS the connection(s) form an unmistakable architectural unity, such as an arch-shaped building (examples: Genex Tower, Dusit Dubai, Umeda Sky Building). Skybridges are generally not sufficient to unify two separate towers. Any structures which adjoin each other for more than 1/3 of any of their heights should be considered 1 building UNLESS: they were built as separate structures and neither one can be considered an addition to the other; this means that the interiors are not integrated at any level, including the ground floor or basement; or the structures are separated at ground level and connected for most of their heights but are normally considered separate buildings; or an addition to a building forms a significant architectural disjunction. An addition on top of an existing building is never counted as a separate building from the one underneath unless it overhangs the lower building from another base. About Skyscrapers The word "skyscraper" was coined in the late 19th Century, reflecting public amazement at the tall buildings being built in New York City. The structural definition of the word "skyscraper" was created later by architectural historians, based on engineering developments of the 1880's which had enabled construction of tall multistory buildings. This definition was based on the steel skeleton, as opposed to constructions of load-bearing masonry which passed their practical limit in 1891 with the Monadnock Building. The steel frame developed in stages of increasing self-sufficiency, with several buildings in New York and Chicago advancing the technology which allowed the steel frame to carry a building on its own.

I dont think there is set amount as a rule.. When they were first built they were 13-14 stories. But if you built a 13 story building today it would hardly be considered a skyscraper...

When a building's height is ten stories or higher.

The first skyscraper of the world is the Home Insurance Building with exact 10 stories(added 2 after building): http://www.pbs.org/wgbh/buildingbig/wonder/structure/home_insurance.html So, buildings with ten stories can be called as a skyscraper.