For reference, a US survey foot is legally defined as 1200⁄3937 meters, which is ~0.304801 meters. The difference is usually written as 2ppm, for practical pur

For reference, a US survey foot is legally defined as 1200⁄3937 meters, which is ~0.304801 meters. The difference is usually written as 2ppm, for practical purposes. (To match units for survey equipment accuracy.)