Convert Miles per Hour to Knots - Speed Converter
This converter transforms a speed value expressed in miles per hour (mph, statute miles per hour) into nautical knots (kn, nautical miles per hour). Knots are used in maritime and aviation contexts and are based on the international nautical mile.
The tool uses the internationally agreed definitions of the statute mile and the nautical mile so the mathematical conversion is deterministic. For critical uses (navigation, regulated reporting, instrumentation), follow the calibration and uncertainty guidance below and verify values against certified instruments or charts.
Governance
Record 29251ef6fd44 • Reviewed by Fidamen Standards Committee
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Methodology
Definitions: 1 statute mile is defined as exactly 1,609.344 meters. 1 international nautical mile is defined as exactly 1,852 meters. These exact definitions are used to compute the conversion factor.
Conversion practice and precision: the converter applies the exact metric-based definitions to compute an exact rational factor. Display precision should match the use case: two to four significant figures for general display, and more digits for engineering, scientific, or regulatory reporting. When used for navigation, include measurement uncertainty and round per the receiving system's requirements.
Calibration and compliance: for measurement instruments and reporting that affect safety or legal compliance, use instruments calibrated to nationally or internationally recognized labs (for example, ISO/IEC 17025 accredited labs). Follow guidance from standards bodies on measurement uncertainty (see citations).
Key takeaways
This converter uses exact international definitions to convert mph to knots with a factor of approximately 0.8689762419. For casual use a few decimal places are sufficient; for regulated or safety-critical contexts follow calibration and reporting standards and include uncertainty estimates.
Worked examples
1 mph = 0.8689762419 kn (commonly shown as 0.8690 kn when rounded to four decimal places).
60 mph = 60 × 0.8689762419 = 52.138574514 kn (displayed as 52.1386 kn for four decimal places).
100 mph = 86.89762419 kn (displayed as 86.8976 kn when rounded to four decimal places).
F.A.Q.
Why is a nautical knot different from miles per hour?
A knot is one nautical mile per hour. A nautical mile (1852 m) is based on the Earth's meridian and historically tied to one minute of arc of latitude; a statute mile (1609.344 m) is a different length. Because these base lengths differ, their per-hour speed units differ by a fixed conversion factor.
How many significant digits should I use?
For general display use 2–4 significant digits. For navigation, meteorology, or engineering, match the precision required by procedures or instruments and include measurement uncertainty. High-precision applications may require carrying additional significant figures internally before final rounding.
Is the conversion exact?
The conversion uses exact international definitions for the statute mile and the nautical mile (both defined in meters), so the computed factor is exact based on those definitions. However, reported values are typically rounded and subject to measurement uncertainty when derived from instruments.
What precautions should I take for navigation or safety-critical use?
Use properly calibrated instruments, document measurement uncertainty, and follow relevant standards and operational procedures. Do not rely solely on an on-screen conversion for navigation; verify with certified instruments, official charts, and onboard systems.
Where do these unit definitions and best practices come from?
Unit definitions are set by international agreements and standards bodies; measurement and calibration practices are guided by national measurement institutes and consensus standards. See the citations for authoritative sources and accreditation guidance.
Sources & citations
- NIST - SI Units and Unit Conversion Reference — https://www.nist.gov/pml/weights-and-measures/si-units
- ISO - International Organization for Standardization — https://www.iso.org
- IEEE Standards Association — https://standards.ieee.org
- OSHA - Occupational Safety and Health Administration — https://www.osha.gov
- ISO 80000-3:2019 — Space and time — https://www.iso.org/standard/64974.html
- NIST SP 811 — Guide for the Use of the International System of Units — https://www.nist.gov/pml/special-publication-811
Further resources
Related tools
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: 29251ef6fd44What changed (latest)
v1.0.0 • 2025-11-20 • 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
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
What changed (latest)
v1.0.0 • 2025-11-20 • 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
UI
v1.0.0
Governance
Last updated: Nov 20, 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 • 2025-11-20 • 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: 4e2ed7142135