Convert Foot (US Survey) (ft (US)) to X-unit (X) instantly.
About these units
Foot (US Survey) (ft (US))
The US Survey Foot is a standardized version of the foot, defined as exactly 1200/3937 meters (~0.30480061 m). It was adopted to maintain continuity with older surveying records when converting to the metric system. Surveyors, engineers, and geographers in the United States used this unit for mapping, cadastral surveys, and infrastructure projects. Its slight difference from the international foot allows historical survey data to align accurately with modern geodetic coordinates. Although the international foot is now more common, the US survey foot remains relevant for interpreting historical survey data and legal property boundaries.
X-unit (X)
The X-unit is an extremely small length, approximately 1.002 × 10⁻¹³ meters, historically used to express X-ray and gamma-ray wavelengths. The unit was invented before modern standards for measuring electromagnetic wavelengths existed, allowing scientists to describe extremely short wavelengths without resorting to scientific notation. X-units were valuable in crystallography and atomic physics in the early 20th century, enabling precise description of spectral lines emitted by X-ray sources. Although modern practice has largely replaced the X-unit with the nanometer or picometer, it continues to appear in historical literature. The unit's existence highlights how scientific progress shapes measuring conventions. Once essential, the X-unit now serves as a bridge to the history of early atomic research.