Knots to Meters per Second Converter | knot to m/s

What this converter does

Knots are how speed is quoted at sea and in the air, but the moment that speed has to go into a calculation or sit beside scientific data, it needs to be in metres per second. This converter takes a speed in knots and gives you m/s. Enter the knots and read off the SI figure.

The conversion factor

One knot is one nautical mile per hour, and a nautical mile is 1,852 metres, so spread over the 3,600 seconds in an hour, one knot is 0.514444 metres per second:

m/s = knots × 0.514444

That figure is the knot written in the language of physics. The m/s value comes out about half the knots, since a metre per second is a much larger step than a single knot.

A quick estimate

The factor is close to 0.514, so for a fast figure, just over half the knots value gets you there. Take 20 knots, half is 10, nudge it up a touch and you land near 10.3 m/s, which is the exact answer. Halving and adding a sliver is an easy way to bring a knot speed into m/s when you only need a rough sense of it.

A worked example

Say a wind is blowing at 20 knots and you need it in m/s to feed into an engineering or physics calculation.

• 20 × 0.514444 = 10.3 m/s

So 20 knots is about 10.3 m/s. That is the number a formula can use, whether you are working out a force on a structure, the load on a sail, or comparing the wind against data published in SI units. The knot figure on its own will not slot into the maths; this is what makes it usable.

Common knots in m/s

As anchors, 10 knots is about 5.1 m/s, and a 40 knot gale works out near 20.6 m/s.

When you need it

This is the direction for taking an operational speed into science. Engineers convert a wind in knots to m/s when working out forces, whether on a building, a turbine, or a sail. Researchers do the same to line a marine or aviation figure up with data recorded in SI units. It also comes up in study and analysis, where a knot reading has to enter a formula written in metres and seconds before any calculation can run. Any time a knot speed is the input to maths or a comparison against scientific data, this conversion prepares it.

Questions people ask

How do I convert knots to m/s?

Multiply the speed in knots by 0.514444. For a quick estimate, take just over half the knots figure.

What is 20 knots in m/s?

About 10.29 m/s. It is a handy anchor, since just over half of 20 lands you on the figure.

Why is the m/s figure about half the knots?

One knot is roughly 0.514 m/s, since a nautical mile spread over an hour is a little over half a metre each second. So the m/s value comes out around half the knots.

References

1. National Institute of Standards and Technology (NIST), Special Publication 811, Guide for the Use of the International System of Units (unit conversion factors). https://www.nist.gov/pml/special-publication-811
2. National Oceanic and Atmospheric Administration (NOAA), National Ocean Service, What is the difference between a nautical mile and a knot? https://oceanservice.noaa.gov/facts/nautical-mile-knot.html