Why is the UK nautical mile longer than the international nautical mile?

The UK nautical mile, or Admiralty nautical mile, was defined as exactly 6,080 feet (1,853.184 metres), making it slightly longer than the international nautical mile, which is exactly 1,852 metres.

What is a chain and where was it traditionally used?

A chain is a traditional surveying length unit equal to 66 feet (approximately 20.1168 metres), commonly used historically in land surveying, cadastral mapping, and measuring parcels of land.

When would I need to convert from nautical mile (UK) to chain?

This conversion is useful when working with historical maritime navigation records, old property surveys, or engineering documents that use UK nautical miles alongside imperial surveying units like chains.

How to Convert from Nautical mile (UK) [NM (UK)] to Chain [ch]

A comprehensive guide for converting measurements from the UK nautical mile (NM (UK)) to the traditional surveying unit called chain (ch), useful for historical navigation and land measurement contexts.

Nautical mile (UK) [NM (UK)]

Chain [ch]

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Nautical mile (UK) [NM (UK)] to Chain [ch] Conversion Table

Nautical mile (UK) [NM (UK)]	Chain [ch]

Custom Unit Conversion Table Generator – Instant Printable Conversion Tables

Start Value

Enter the starting number (positive decimal or integer ≥ 0). Example: 0.1, 1, 5.

End Value

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Interval

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Nautical mile (UK) [NM (UK)] to Chain [ch] Conversion Table
Nautical mile (UK) [NM (UK)]	Chain [ch]

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What Is This Tool?

This tool enables you to convert measurements from the UK nautical mile, historically known as the Admiralty nautical mile, into chains, a traditional land surveying length unit. It is designed to assist with interpreting and reconciling historical maritime and cadastral records.

How to Use This Tool?

Enter the value in nautical miles (UK) you wish to convert.
Select the output unit as chain [ch].
Initiate the conversion to get the result in chains.
Use the converted value to interpret or compare historical measurements.

Key Features

Supports conversion between UK nautical mile (exactly 6,080 feet) and chain (66 feet).
Ideal for handling historical navigation and surveying data.
Includes commonly used conversion rates for ease of calculation.
Browser-based and easy-to-use interface for quick conversions.

Examples

Convert 1 NM (UK) to chain: 1 NM (UK) = 92.12 ch
Convert 0.5 NM (UK) to chain: 0.5 NM (UK) = 46.06 ch

Common Use Cases

Interpreting distances on historical UK Admiralty charts and logs recorded in NM (UK).
Converting legacy maritime or legal documents for integration with SI units.
Comparing and restoring older navigation instruments and datasets.
Interpreting historical cadastral surveys and land measurement records.
Converting property deeds and survey plans for GIS land registration.
Understanding engineering and agricultural records that use imperial surveying units.

Tips & Best Practices

Verify whether the nautical mile referenced is UK or international before converting.
Use conversions primarily for historical or archival data interpretation.
Refer to original documents to confirm unit definitions when possible.
Apply converted values for comparison rather than precise modern navigation.

Limitations

The UK nautical mile differs slightly from the international nautical mile, so modern navigation calculations typically use the international definition.
Chains are largely obsolete in present-day surveying, so this conversion mainly applies to historical or archival contexts.
Conversions do not support contemporary precise surveying needs due to unit obsolescence.

Frequently Asked Questions

Why is the UK nautical mile longer than the international nautical mile?: The UK nautical mile, or Admiralty nautical mile, was defined as exactly 6,080 feet (1,853.184 metres), making it slightly longer than the international nautical mile, which is exactly 1,852 metres.
What is a chain and where was it traditionally used?: A chain is a traditional surveying length unit equal to 66 feet (approximately 20.1168 metres), commonly used historically in land surveying, cadastral mapping, and measuring parcels of land.
When would I need to convert from nautical mile (UK) to chain?: This conversion is useful when working with historical maritime navigation records, old property surveys, or engineering documents that use UK nautical miles alongside imperial surveying units like chains.

Key Terminology

Nautical mile (UK) [NM (UK)]: A historical unit of length defined as exactly 6,080 feet or 1,853.184 metres, used mainly in UK maritime navigation.
Chain [ch]: A traditional surveying unit of length measuring 66 feet or about 20.1168 metres, commonly used in land measurement and cadastral surveys.
Admiralty nautical mile: Another name for the UK nautical mile, historically used in British Admiralty charts and maritime navigation.

Quick Knowledge Check

What length does the UK nautical mile correspond to?

Exactly 1,852 metres

Exactly 6,080 feet

Exactly 20.1168 metres

How many feet are in one chain?

66 feet

100 feet

6,080 feet

For what purpose is the conversion from NM (UK) to chains mostly applied today?

Modern precise navigation

Historical or archival contexts

Real-time maritime tracking

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