Convert Nautical Miles to Kilometers – Length Converter
This tool converts nautical miles (nmi) to kilometres (km) using the internationally accepted definition of the nautical mile. It is intended for navigation, engineering, mapping, aviation and marine planning where distances are commonly expressed in nautical miles but calculations or reporting require metric units.
The conversion implemented here uses the exact definition adopted by international agreement: one nautical mile equals 1,852 metres. This makes the conversion deterministic and suitable for high-accuracy distance work. See the methodology and citations for standards and guidance on precision, rounding and traceability.
Interactive Converter
Convert between nautical mile and kilometer with precision rounding.
Quick reference table
| Nautical Mile | Kilometer |
|---|---|
| 1 nmi | 1.852 km |
| 5 nmi | 9.26 km |
| 10 nmi | 18.52 km |
| 25 nmi | 46.3 km |
| 50 nmi | 92.6 km |
| 100 nmi | 185.2 km |
Methodology
By international convention the nautical mile is defined as exactly 1852 metres. That definition is used by national standards bodies and international organizations for navigation and mapping. Converting to kilometres therefore reduces to a fixed scalar multiplication: multiply nautical miles by 1.852 to get kilometres.
When reporting or using converted distances in regulated contexts, follow local measurement traceability and documentation requirements. For engineering or safety-critical uses follow guidance from recognized standards organizations (for example NIST for unit definitions and uncertainty, ISO for quantities and units, IEEE when communicating units in technical documents, and OSHA where metric reporting is required for safety records).
Worked examples
1 nmi → 1 × 1.852 = 1.852 km
0.5 nmi → 0.5 × 1.852 = 0.926 km
10 nmi → 10 × 1.852 = 18.52 km
100 nmi → 100 × 1.852 = 185.2 km
Key takeaways
The nautical mile → kilometre conversion uses an exact scalar (1 nmi = 1.852 km).
Use appropriate rounding and record uncertainty when converting for reporting, regulatory or safety purposes.
Refer to the cited standards for authoritative definitions and requirements for traceability and unit notation.
Further resources
Expert Q&A
Is the conversion between nautical miles and kilometres exact?
Yes. By international agreement one nautical mile is defined as exactly 1,852 metres, so converting to kilometres (1 km = 1,000 m) yields an exact factor of 1.852. Any non-exactness in results comes from numeric rounding when displaying values.
Where does the value 1.852 come from?
Historically the nautical mile was defined relative to the Earth's circumference; the modern international nautical mile has been fixed at 1,852 metres by international standards bodies. See the cited standards for the formal definition and history.
How many decimal places should I use?
Choose precision based on context: navigation and charting often use one or two decimal places for operational readability, while engineering or scientific work should include uncertainty estimates and use enough precision to reflect measurement tolerances. When in doubt, keep at least three significant digits and document rounding.
When should I use nautical miles instead of kilometres?
Nautical miles are standard in marine and aviation contexts because they relate directly to minutes of latitude and navigation charts. Use kilometres for land-based metric reporting or when mandated by regulatory or engineering standards.
Do I need to record measurement uncertainty when converting?
Yes for regulated, safety-critical, or precision engineering contexts. Converting the unit itself is exact, but the original distance may carry measurement uncertainty. Follow guidance from standards bodies (for example NIST and ISO) when documenting uncertainty and traceability.
Sources & citations
- NIST Reference — Units, Symbols, and Abbreviations — https://physics.nist.gov/cuu/
- ISO — Quantities and units (ISO 80000 series) — https://www.iso.org/standard/30669.html
- IEEE Standards Association — Standards resource center — https://standards.ieee.org/
- OSHA — United States Department of Labor — https://www.osha.gov/