Convert Nautical Mile (nmi) to Chain (ch) 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 (ch)
A chain is equal to 66 feet or 4 rods, and it was standardized by surveyor Edmund Gunter in the 17th century. "Gunter's chain," consisting of 100 metal links, became the backbone of land surveying in the English-speaking world for centuries. Its convenience stems from simple arithmetic: 10 square chains make an acre, making land area calculations straightforward. Railroads, farmland, and city parcels across the United States and the Commonwealth nations were once laid out using chains, so the unit appears in countless historical records. Even today, some legal property descriptions still reference chain-based measurements, making the unit relevant for modern surveyors who interpret old maps. Although high-precision digital equipment has replaced physical chains, the unit's structural role in land division ensures its lasting importance.