A coordinate system in U.S. survey feet may be converted to a coordinate system in meters by scaling the system to a scale factor of 0.304800609601. An exact conversion can be accomplished by multiplying U.S. survey feet by the fraction 1200/3937.

A coordinate system in meters may be converted to a coordinate system in U.S. survey feet by scaling the system to a scale factor of 3.28083333333. An exact conversion can be accomplished by multiplying meters by the fraction 3937/1200.

The foot is one-third of the Imperial standard yard, which is defined to be 0.9144 meters, exactly. Thus the foot is defined as 0.3048 meters, exactly.


Discussion:

In 1959, the directors of the National Bureau of Standards and the United States Coast and Geodetic Survey agreed on a redefinition of the inch-centimeter relationship. This redefinition defined 1 inch as equal to 2.54 centimeters, exactly, or 1 foot as equal to 0.3048 meters, exactly.

However, their agreement stipulated that the older value for 1 meter equaling 39.37 inches, exactly, be retained for identifying the U.S. survey foot.

One of the reasons for this retention was that the State Plane Coordinate Systems, which are derived from the national geodetic control network, are based on the relationship of 1 meter equaling 39.37 inches, exactly.

The difference between these two values for the foot is very small, two parts per million, which is hardly measurable but not trivial when computational consistency is desired. Fundamental survey units, such as rods, chains, statute miles, acres, sections, and townships, all depend on the relationship of 1 meter equaling 39.37 inches, exactly.

The preceeding list represents the corrected values (or U.S. survey values), using the 39.37-inch conversion value.