Mph to Knots
Convert miles per hour to knots with the exact factor (1 mph = 0.868976 kn), a quick reference table, and common aviation and boating speeds.
mph to kn formula
To convert miles per hour (mph) to knots (kn), multiply by 0.868976. One knot = 1 nautical mile per hour = 1.15078 mph, so 1 / 1.15078 = 0.868976 kn.
Quick reference: mph to kn
Common values
1 mph = 0.869 kn
10 mph = 8.69 kn
55 mph = 47.79 kn
60 mph = 52.14 kn
100 mph = 86.9 kn
Worked example
Convert 60 mph to knots:
60 mph × 0.868976 = 52.1386 kn
So 60 mph is about 52.1 knots.
Why convert mph to kn?
Road speed is in mph, but aviation and maritime navigation use knots. This conversion links the two speed scales.
You can also use our calculator or read the paired guide kn reference.
Frequently Asked Questions
How many knots are in a mph?
1 mph = 0.868976 kn.
How many mph are in a knot?
1 knot = 1.15078 mph.
How do I convert 100 mph to knots?
100 mph × 0.868976 = 86.8976 kn.
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Quick Summary
mph to kn uses a single exact factor. Use the formula above or the reference table for quick, accurate results.
Related Guide
Knots to MPH Conversion: Guide for Aviation and Marine Speeds
Convert knots to mph for aviation and marine weather reading. 1 knot equals 1.15078 mph, so 20 knots equals 23.02 mph in this practical guide.
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Disclaimer
Unit conversions on this site use internationally recognized, fixed conversion factors (for example, 1 inch = 2.54 cm, 1 pound = 0.45359237 kg, 1 °F = (°C × 9/5) + 32). They are provided for general, informational, and educational use. For applications where accuracy is critical — such as medical dosing, engineering, scientific research, trade, or legal compliance — always verify results against authoritative sources such as the U.S. National Institute of Standards and Technology (NIST) and the official International System of Units (SI) brochure, and follow any applicable local standards.
Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 mile per hour (mph) = 1.609344 km/h (exact, 1 mi/h)
- EXACT1 mph = 0.44704 metres per second (exact)
- EXACT1 km/h = 1/3.6 m/s (exact reciprocal)
- EXACT1 knot = 1.852 km/h (exact, 1 nautical mile/h)
Common Pitfalls & How to Avoid Them
mph vs. km/h is not a 2× rule
1 mph = 1.609344 km/h. A 60 mph limit is 96.56 km/h, not 120. The factor is ~1.6, not 2.
Knots are nautical
Aviation and marine speeds use knots (1.852 km/h). Confusing a 30-knot wind with 30 mph understates it by ~17%.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This article was reviewed for accuracy