A knot is one nautical mile per hour. A nautical mile (1,852 metres) is based on the Earth’s geometry, which makes knots convenient for navigation. Knots are the standard speed unit in aviation, shipping and meteorology.

How many knots is 100 mph?

100 miles per hour is about 86.90 knots. Some handy values: 20 mph ≈ 17.38 kn, 50 mph ≈ 43.45 kn and 200 mph ≈ 173.80 kn. The converter shows the exact value for any figure you enter.

Why is a speed in knots lower than the same speed in mph?

Because a nautical mile is longer than a statute mile, you cover fewer nautical miles than statute miles in the same time. So a given speed is a smaller number in knots than in mph — one mph is about 0.869 knots.

When should I convert mph to knots?

It is common in sailing, boating, aviation and weather, where a speed given in miles per hour needs to be read in knots — the standard nautical and aviation unit.

Can this tool convert knots back to mph?

Yes. Tap the ⇄ swap button to reverse the direction and convert knots to miles per hour (multiply by 1.15078). You can also pick any other speed unit from the dropdown, since this page runs on our full Mega Speed Converter.

Does the converter update live and work on mobile?

Yes. The knot result recalculates instantly as you type — there is no submit button — and the layout adapts to phones. A ready-made miles-per-hour-to-knots table is included for the most common values.

Miles per Hour to Knots Converter

Convert miles per hour to knots instantly. A knot is one nautical mile per hour, used in aviation, marine navigation and weather. Because a nautical mile (1,852 m) is longer than a statute mile (1,609.344 m), one mile per hour is about 0.868976 knots. So to go from miles per hour (mph) to knots (kn) you multiply by 0.8…

VALUE & FROM

0.86897624

1 mile per hour = 0.86897624 knot · 1 mile per hour = 0.86897624 knot

1 mile per hour IN EVERY UNIT

METRIC

IMPERIAL / US

NAUTICAL

PHYSICS

HISTORICAL & FUN

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HOW TO USE

1
Enter the speed in miles per hour (mph) in the value box — the converter defaults to mph → knots.
2
Read the knot (kn) result instantly, or do it by hand: multiply the mph value by 0.868976.
3
Use the mph-to-knots table below for common values, or tap ⇄ to convert knots back to miles per hour.
4
Need another unit? Pick any of the 21 speed units in the dropdown, then Share or Embed your conversion.

QUICK REFERENCE

1 km/h

0.621371 mph

1 mph

1.609344 km/h

1 m/s

3.6 km/h

1 m/s

2.23694 mph

1 knot

1.852 km/h

1 knot

1.15078 mph

1 mph

1.46667 ft/s

1 Mach

1,225.04 km/h

1 mi/s

3,600 mph

1 ft/s

0.681818 mph

ABOUT SPEED UNITS

Speed is distance divided by time, and its SI unit is the metre per second (m/s). The two most common everyday units are the kilometre per hour (km/h) and the mile per hour (mph): one metre per second is exactly 3.6 km/h and about 2.237 mph, while 1 km/h is about 0.621 mph. At sea and in the air, speed is measured in knots — one knot is one nautical mile per hour, or exactly 1.852 km/h. Very high speeds use the Mach number, the ratio of an object's speed to the local speed of sound; at sea level in standard conditions that is about 340.29 m/s (1,225 km/h), but it falls as air gets colder or thinner, so Mach 1 is not a fixed speed. The ultimate limit is the speed of light in a vacuum, exactly 299,792,458 m/s. Every unit here is stored as its exact number of metres per second, so any conversion is just the input turned into m/s and then into the target unit. Note that running or cycling pace (minutes per kilometre or per mile) is the reciprocal of speed rather than a linear unit, so it is handled by a separate pace calculator and is not part of this tool.

FREQUENTLY ASKED QUESTIONS

Multiply the number of miles per hour by 0.868976 (or divide by 1.15078). This follows from a nautical mile being longer than a statute mile. For example, 50 mph × 0.868976 ≈ 43.45 knots. The converter does this instantly.

Formula: knots = mph × 0.868976.
A nautical mile is longer than a statute mile.
50 mph ≈ 43.45 kn; 20 mph ≈ 17.38 kn.
To reverse it, multiply knots by 1.15078.

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Last updated: — · 21 speed units · Exact SI, imperial & nautical definitions · Verified by the EagleCalculator team · Eagle-eyed accuracy for every calculation.