Boat Speed Calculator
Convert boat speed between knots, mph and km/h.
About the Boat Speed Calculator
Converts a vessel's speed between knots, miles per hour and kilometres per hour, and estimates travel time over a distance.
$$ 1\ knot = 1.852\ km/h $$
How to use
Enter a speed, its unit, and optionally a distance in nautical miles, then click Calculate.
Worked example
20 knots = 23.0 mph = 37.0 km/h.
How to use this calculator
- Choose the speed value and the unit you already know.
- Enter the number into the calculator.
- Select the unit you want to convert to and view the result instantly.
The formula explained
$$ \text{mph} = 1.15078 \times \text{knots}, \quad \text{km/h} = 1.852 \times \text{knots}, \quad \text{knots} = \frac{\text{mph}}{1.15078}, \quad \text{knots} = \frac{\text{km/h}}{1.852} $$
- \(\text{knots}\) = boat speed measured in knots
- \(\text{mph}\) = speed measured in miles per hour
- \(km/h\) = speed measured in kilometers per hour
Step by step method
- Start with the given boat speed and confirm whether it is in knots, mph, or km/h.
- Use the matching conversion factor to translate the value into the target unit.
- Check the displayed result and, if needed, compare it with a second unit for context.
Worked example
Suppose a boat is cruising at 20 knots and you want to know its speed in miles per hour and kilometers per hour.
- Convert knots to mph using \(20 \times 1.15078 = 23.0156\).
- Convert knots to km/h using \(20 \times 1.852 = 37.04\).
Answer. 20 knots equals 23.02 mph and 37.04 km/h.
Tips and common mistakes
- Remember that knots measure nautical miles per hour, not statute miles per hour.
- If you are converting from mph or km/h to knots, use the inverse conversion factor.
- Small rounding differences are normal, especially when the calculator shows results to two decimal places.
- Make sure you do not mix up mph and km/h, since they are close but not the same.
Frequently asked questions
What is a knot?+
One nautical mile per hour; 1 knot = 1.852 km/h ≈ 1.151 mph.
Why do boats use knots?+
Nautical miles relate directly to latitude, simplifying chart navigation.
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