Convert Kilometers to Nautical Miles – Length Converter

This tool converts a distance given in kilometres (kilometers) into international nautical miles. The international nautical mile is defined exactly as 1852 metres and is the standard used in maritime and aviation contexts.

Use this converter for chart reading, flight planning, navigation calculations, or general unit conversion. Results are presented as a direct mathematical conversion; follow the guidance below on rounding and regulatory compliance for operational use.

Updated Nov 10, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 3d05ddeb586f • Reviewed by Fidamen Standards Committee

Interactive Converter

Convert between kilometer and nautical mile with precision rounding.

Kilometer (km)Nautical Mile (nmi)

Quick reference table

Kilometer	Nautical Mile
1 km	NMI 0.54 nmi
5 km	NMI 2.6998 nmi
10 km	NMI 5.3996 nmi
25 km	NMI 13.4989 nmi
50 km	NMI 26.9978 nmi
100 km	NMI 53.9957 nmi

Methodology

Conversion is performed using the international nautical mile definition of exactly 1852 metres. One kilometre equals 1000 metres, therefore the exact ratio is 1000/1852 nautical miles per kilometre.

Displayed numeric results are produced from standard IEEE-754 double-precision arithmetic and then rounded for presentation. For formal or regulated workflows, follow the rounding, reporting, and documentation rules required by relevant authorities and standards organizations.

Key takeaways

Use the exact ratio 1 km = 1000/1852 nmi (≈ 0.5399568034557234) for conversions.

Round results based on context and applicable regulations. For safety-critical applications, follow formal procedures and maintain instrument calibration records.

Worked examples

Example 1: 1 kilometre → 1 × (1000 ÷ 1852) = 0.5399568034557234 nautical miles. Rounded to three decimals: 0.540 nmi.

Example 2: 10 kilometres → 10 × (1000 ÷ 1852) ≈ 5.399568034557234 nautical miles. Rounded to two decimals for display: 5.40 nmi.

Example 3: 123.456 kilometres → 123.456 × (1000 ÷ 1852) ≈ 66.663 nmi when rounded to three decimal places.

F.A.Q.

Which definition of the nautical mile does this converter use?

This converter uses the international nautical mile defined as exactly 1852 metres, which is the standard in aviation and maritime navigation.

How many decimal places should I use for operational navigation?

Decimal places depend on context. For chart-level distances, two or three decimals are typically sufficient. For precision navigation or instrument flight planning, follow the accuracy and rounding rules in your operational procedures and applicable regulations.

Are there alternative definitions of the nautical mile?

Historically other definitions existed, but the internationally accepted definition is 1852 metres. Use the international definition for modern navigation and regulatory compliance.

What are the accuracy limitations of the calculator?

The mathematical conversion uses exact unit definitions but numeric results are subject to floating-point rounding per IEEE-754. For legal, safety-critical, or certified measurements, refer to official instrument calibration records and standards and report values according to the required number of significant figures.

Can I convert back from nautical miles to kilometres?

Yes. Use the reciprocal factor: kilometres = nautical miles × 1.852. For convenience, use a two-way converter or perform the reciprocal operation as needed.

Sources & citations

NIST Special Publication 811 - Guide for the Use of the International System of Units (SI) — https://www.nist.gov/pml/special-publication-811
BIPM - Units and Definitions (SI Brochure) — https://www.bipm.org/en/measurement-units/
ISO 80000 series — Quantities and units (space and time) — https://www.iso.org/standard/64949.html
IEEE 754-2019 Standard for Floating-Point Arithmetic — https://standards.ieee.org/standard/754-2019.html
OSHA - Occupational Safety and Health Administration — https://www.osha.gov/
BIPM SI Brochure (9th edition, 2019) — https://www.bipm.org/en/publications/si-brochure

Further resources

Related tools

External guidance

Versioning & Change Control

Audit record (versions, QA runs, reviewer sign-off, and evidence).

Record ID: 3d05ddeb586f

What changed (latest)

v1.0.0 • 2025-11-10 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Public QA status

PASS — golden 25 + edge 120

Last run: 2026-01-23 • Run: golden-edge-2026-01-23

Engine

v1.0.0

Data

Baseline (no external datasets)

Content

v1.0.0

Governance

Last updated: Nov 10, 2025

Reviewed by: Fidamen Standards Committee (Review board)

Credentials: Internal QA

Risk level: low

Reviewer profile (entity)

Fidamen Standards Committee

Review board

Internal QA

Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person

Semantic versioning

MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
MINOR: New features or fields that do not change existing outputs for the same inputs.
PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.

Review protocol

Verify formulas and unit definitions against primary standards or datasets.
Run golden-case regression suite and edge-case suite.
Record reviewer sign-off with credentials and scope.
Document assumptions, limitations, and jurisdiction applicability.

Assumptions & limitations

Uses exact unit definitions from the Fidamen conversion library.
Internal calculations use double precision; display rounding follows the unit's configured decimal places.
Not a substitute for calibrated instruments in regulated contexts.
Jurisdiction-specific rules may require official guidance.

Change log

v1.0.0 • 2025-11-10 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 897f59820e46