# Chains to Nautical Miles (ch to nmi) Source: https://www.unitconvertercalculator.com/length/chains-to-nautical-miles/ **1 ch = 0.010862203023758 nmi** One chain equals approximately 0.01087 nautical miles. Since 1 chain = 20.1168 m and 1 nautical mile = 1,852 m, the ratio is 20.1168/1852. About 92 chains make one nautical mile. Both units come from the British measurement tradition but serve different domains: chains for land, nautical miles for sea. ## Formula Convert Chains to Nautical Miles ## Conversion Table | Chains (ch) | Nautical Miles (nmi) | |---|---| | 1 ch | 0.010862203023758 nmi | | 5 ch | 0.054311015118791 nmi | | 10 ch | 0.10862203023758 nmi | | 20 ch | 0.21724406047516 nmi | | 40 ch | 0.43448812095032 nmi | | 80 ch | 0.86897624190065 nmi | | 100 ch | 1.0862203023758 nmi | | 200 ch | 2.1724406047516 nmi | | 500 ch | 5.4311015118791 nmi | | 1000 ch | 10.862203023758 nmi | | 5000 ch | 54.311015118791 nmi | | 10000 ch | 108.62203023758 nmi | ## Units ### Chain (ch) Exactly 66 feet or 4 rods (20.1168 m). Invented by Edmund Gunter for land surveying. 80 chains make one mile. Still used in US public land surveys. ### Nautical Mile (nmi) Exactly 1852 meters by international agreement. Based on one minute of arc of latitude at the Earth's surface. The standard unit for maritime and air navigation. ## Background About 92 chains make one nautical mile. A 12-nautical-mile territorial waters boundary is about 1,106 chains from shore. While both units originated in the British Empire, they were never used together: surveyors stayed on land with chains, sailors stayed at sea with nautical miles. ## Good to Know The British Empire used chains on land and nautical miles at sea, but never mixed them. A coastal boundary was described in chains landward and nautical miles seaward, with the high-water mark as the dividing line. ## FAQ ### How many nautical miles is 1 chain? One chain equals approximately 0.01087 nautical miles. About 92 chains (91.99) make one nautical mile. ### How many chains are in 1 nautical mile? One nautical mile contains approximately 92 chains (91.99 to be precise). Since 1 NM = 1,852 m and 1 chain = 20.1168 m, divide 1,852 by 20.1168. ### Were chains ever used at sea? No. Chains were strictly a land surveying tool. At sea, distances were measured in nautical miles, cable lengths (1/10 NM), and fathoms (for depth). The two measurement systems coexisted in the British Empire but never mixed. ## Non-Frequently Asked Questions ### Can I survey the ocean with a chain? Technically, no. Chains were designed for land. The ocean was measured in nautical miles and fathoms. A chain is about 0.01087 NM - useless for ocean navigation. Dropping a surveyor's chain overboard would measure about 11 fathoms of depth and annoy the captain. ### How many chains from England to France? The English Channel at its narrowest (Dover to Calais) is about 18.2 NM or about 1,674 chains. If Gunter tried to measure the Channel with his chain, he would need a very long rope and a very waterproof chain. ### Were chains ever used at sea? Not surveying chains. But anchor chains on ships are measured in 'shackles' of 15 fathoms (90 feet). A shackle is about 1.36 surveying chains. The nautical world had its own chain units and wanted nothing to do with Gunter's. ## Related Articles - [Why We Measure: The Deepest Urge in Human Civilisation](https://www.unitconvertercalculator.com/blog/why-we-measure) - [The Map Is Not the Territory: Why Every Measurement Is Wrong](https://www.unitconvertercalculator.com/blog/the-map-is-not-the-territory) - [Zero: The Most Dangerous Number in Measurement](https://www.unitconvertercalculator.com/blog/zero-the-most-dangerous-number-in-measurement) - [The Body as a Ruler: Every Measurement Unit That Came From Us](https://www.unitconvertercalculator.com/blog/the-body-as-a-ruler) - [The Speed of Everything: How We Measure From Glaciers to Light](https://www.unitconvertercalculator.com/blog/the-speed-of-everything) - [15 Obscure Measurement Units You've Never Heard Of (But Still Need)](https://www.unitconvertercalculator.com/blog/obscure-measurement-units-guide) - [When Measurements Go Wrong - Disasters, Blunders and Happy Accidents](https://www.unitconvertercalculator.com/blog/when-measurements-go-wrong) - [The Surprising Stories Behind Everyday Units of Measurement](https://www.unitconvertercalculator.com/blog/stories-behind-measurement-units) - [Metric vs. Imperial - The Complete Guide to the World's Two Measurement Systems](https://www.unitconvertercalculator.com/blog/metric-vs-imperial-complete-guide) - [Length & Distance Conversion Guide - Meters, Feet, Miles & Kilometers](https://www.unitconvertercalculator.com/blog/length-and-distance-guide) ## See Also - [Nautical Miles to Chains](https://www.unitconvertercalculator.com/length/nautical-miles-to-chains/)