Knots to miles per hour Converter

How many miles per hour are in a knot?

One knot is 1.150779 miles per hour. The full conversion is miles per hour = knots × 1.150779448, and going the other way you divide instead of multiply.

A few anchor values worth memorising: 1.150779 mph to the knot, 11.507794 mph to ten, and 115.077945 mph to a hundred. The calculator above handles the rest, including the awkward decimals.

The reference table under the converter lists the values people look up most often, so for a common figure you can read the answer off directly rather than typing anything.

Worked examples

Three worked examples, each multiplying by 1.15077945:

2.5 kn × 1.150779 = 2.8769 mph. 25 kn × 1.150779 = 28.7695 mph. 250 kn × 1.150779 = 287.6949 mph.

To reverse any of them, divide instead of multiplying — or use the swap button above, which does the same thing without the arithmetic. Reversing a converted value should return you to exactly what you started with; if it does not, something has been rounded too early.

Doing this conversion in your head

The exact factor is 1.15077945, which nobody multiplies by in their head. It is very close to 8/7, so multiplying by 8 and dividing by 7 lands within 0.69% of the correct answer — accurate enough for anything short of engineering work.

Since the factor is greater than one, the number always gets bigger: a knot is smaller than a mile per hour, so any quantity converts to more of them. If your answer came out smaller, you have divided when you should have multiplied.

That sanity check catches the majority of real conversion errors. Before trusting any converted figure, ask whether the direction of change makes sense — it takes a second and it is the single most effective safeguard there is.

When you need to convert knots to miles per hour

Converting knots into miles per hour is rarely done for its own sake — there is usually a form, a spec or a recipe on the other end of it.

On the source side, knots are the speed unit for ships, aircraft and marine weather forecasts. On the target side, miles per hour is the speed limit in the US and UK, and how wind speeds are reported in US forecasts. The conversion is essentially a translation between those two worlds — most often because a figure produced in one context has to be understood, submitted or acted on in the other.

Where the converted figure will be cut, dosed, billed or filed, round once at the end rather than at each step. For a rough sense of scale, round freely.

Whatever the reason, the arithmetic runs in your browser. Nothing you type is transmitted, logged or stored, and the converter keeps working if you go offline after the page has loaded.

What a knot and a mile per hour actually are

The knot (kn). One nautical mile per hour — the unit of maritime and aviation speed.

The mile per hour (mph). Road speeds in the US and UK, and wind speeds in US weather reports.

Since knots and miles per hour both quantify speed against a common defined standard, nothing is lost in translating between them. The only imprecision anywhere in this page is deliberate rounding for readability.

Common mistakes when converting knots to miles per hour

A knot is one nautical mile per hour, and a nautical mile is one minute of latitude — which is what makes it so useful at sea, since a distance in nautical miles can be read straight off a chart's latitude scale. Saying "knots per hour" is a common error; the "per hour" is already inside the word.

For a batch of figures, set the units once and work down the list rather than converting via a third unit — each intermediate step introduces its own rounding.