Convert Nautical Mile (nmi) to Chain (US Survey) (ch (US)) instantly.
About these units
Nautical Mile (nmi)
The nautical mile is a unit designed specifically for navigation. Its definition—exactly 1,852 meters—originated from the idea that one nautical mile equals one minute of arc along Earth's meridian. This geometric relationship makes nautical miles incredibly convenient for charting and navigation because latitude coordinates are given in degrees, minutes, and seconds. Aviation and maritime industries use nautical miles exclusively for distance, and knots (nautical miles per hour) for speed. Because Earth's shape and size are fundamental to navigational calculations, using nautical miles avoids the complexities that would arise if statute miles or kilometers were used instead. The unit remains globally standardized and universally understood in professional navigation.
Chain (US Survey) (ch (US))
The US Survey Chain is defined as 66 US Survey Feet (~20.1168 meters), aligning with the historic Gunter's chain but adapted to the US survey foot. It is used primarily in cadastral surveys, property delineation, and historical land records. Surveyors employ the chain for practical measurements of fields, lots, and infrastructure layouts. The unit's subdivision into 100 links simplifies area calculation, as 10 square chains equal one acre, maintaining continuity with older surveying systems. Even today, engineers and surveyors working with legacy data encounter the US survey chain in historical deeds, maps, and legal descriptions. Its precision ensures consistency when reconciling pre-modern measurements with modern coordinates.