Convert Rack Unit to Siriometer (U to Siriometer)

Rack Unit (U) and Siriometer (Siriometer) are both units of length. With the conversion form below, you can effortlessly and accurately convert rack unit to siriometer. This free online calculator tool makes it simple and easy to perform the conversion from U unit to the Siriometer unit.

Length is the measure of distance in one dimension—the extent of an object from one end to the other, or the distance between two points. The SI base unit is themeter (m), defined since 1983 as the distance light travels in a vacuum in 1/299,792,458 of a second. Common derived units include the kilometer (1 km = 1,000 m) for distances and the centimeter (cm) and millimeter (mm) for everyday measurements. US customary length units include the inch (in), foot (ft), yard (yd), and mile (mi). The nautical mile (1,852 m) is used in aviation and maritime navigation.

A rack unit (RU or U) is a standardized measurement equal to 1.75 inches (44.45 millimeters) used to specify the height of equipment mounted in server racks and telecommunications enclosures. The measurement standard emerged from the 19-inch rack width standard established in telecommunications infrastructure. Networking equipment, servers, patch panels, and other data center hardware are designed and specified in rack units. A single-unit device (1U) is 1.75 inches tall; a 2U device is 3.5 inches tall; a 4U device is 7 inches tall. Data center architects, network engineers, and equipment procurement specialists use rack units constantly when planning facility layouts, specifying equipment requirements, and managing space allocation in server rooms. The unit remains universal in telecommunications and data center industries worldwide. Learn more about rack unit.

The siriometer (symbol: Sm) is a non-SI unit of length historically used in astronomy to express extremely large distances. One siriometer is equal to one million astronomical units (AU), or approximately 1.495978707 × 10¹⁷ meters. Although it has largely been replaced by the light-year and parsec, the siriometer played an important role in early astronomical literature. More information is available in the siriometer article.

One siriometer is equal to 1,000,000 astronomical units, approximately 15.8125 light-years, approximately 4.84814 parsecs, 149,597,870,700,000 kilometers, and 149,597,870,700,000,000 meters. The siriometer is now considered an obsolete astronomical unit but remains of historical interest in older scientific publications.