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Knots to MPH Converter

Convert knots to MPH with our free knots to mph converter — or flip it and turn miles per hour back into knots. One knot equals 1.15078 mph, so a boat doing 10 knots is moving at 11.51 mph over the water.

Common speeds

How it works

A knot is not the same as a mile per hour, even though both measure speed. A knot is one nautical mile per hour, and a nautical mile is longer than a land mile: 1,852 meters, or about 1.15078 land miles. That is why a speed in knots always looks a little higher in mph — the boat is covering longer miles each hour.

Sailors, pilots, and weather forecasters use knots because nautical miles are tied to the Earth itself: one nautical mile is one minute of latitude, which makes navigation math much simpler on a chart. American drivers, on the other hand, think in miles per hour, so a boater in Florida or California often needs to translate a forecast or a boat's speed into mph to make sense of it.

To convert knots to mph, multiply by 1.15078. To go the other way, divide mph by 1.15078 — or multiply by 0.868976, which gives the same answer. For a quick estimate, add about 15 percent to the knot figure: 10 knots is roughly 11.5 mph, and 20 knots is roughly 23 mph. For trip planning, fuel estimates, or weather decisions, use the exact factor in the converter above.

Wind speed is where this conversion matters most for safety. A forecast of 20 knots sounds mild until you convert it: 23.02 mph, a strong breeze that can make small-boat handling tricky. A 30-knot wind is 34.52 mph, and a 50-knot wind is 57.54 mph — near the threshold of a Category 1 hurricane, which begins around 64 knots (74 mph). Knowing the mph figure helps you compare a marine forecast with the wind speeds you are used to on land.

Worked example

Tom in Miami is planning a fishing trip. His boat cruises at 10 knots, and he wants to know how fast that is in miles per hour so he can estimate how long the 23-mile run to his fishing spot will take.

Step 1: Write down the speed — 10 knots.
Step 2: Use the conversion factor — 1 knot = 1.15078 mph.
Step 3: Multiply: 10 × 1.15078 = 11.5078.
Step 4: Round to two decimal places — 11.51 mph.

That is the exact result this converter gives for 10 knots: 11.51 mph. At 11.51 mph, the 23-mile run takes 23 ÷ 11.51 = 2.0 hours, so Tom should plan on about two hours each way — and a little extra if the wind picks up.

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