Como comparar mph vs km

This speed conversion calculator enables you to convert between 18 different units of speed measurement in real-time. Choose between popular units, such as kilometers per hour, meters per second, feet per second, miles per hour and knots, or pick some more obscure ones, such as those used in astronomy like kilometers per second or the speed of light. Enter your known value, and you will instantly see the results in 4 other units.

While this simple tool converts from one unit to another, the speed calculator works out speed based on time and distance. If you are a sports enthusiast, you may find our running pace calculator useful .

The speed of an object is the distance it covers in a certain amount of time, without any regard to the direction of travel. The related term, velocity, uses vectors or positive and negative values to indicate direction.

For example, if in an hour you drive 🚗 40 miles, then your speed (at least your average speed) is 40 miles per hour (mph).

You may not be familiar with all of the units present in this speed conversion calculator. Feet per second and miles per hour are units commonly used in countries that use the imperial system, such as the United States, the United Kingdom, and Australia. On the other hand, meters per second and kilometers per hour are the units of choice for those nations that use the metric system, i.e., the rest of the world.

If you are looking to take to the high seas, then knots are your unit of choice (they are used regardless of your affiliation to the imperial or metric systems). One knot equals one nautical mile per hour (approximately 1.151 mph).

To convert from one speed unit to another, it is simply a case of multiplying the speed by the correct conversion factor. In equation form, we can write:

converted speed = original speed * conversion factor

So, for example, to convert from mph to kmh (miles per hour to kilometers per hour), we use a conversion factor of 1.609344. Let's try it out and convert 200 mph to kmh:

speed in kmh = 200 mph * 1.609344 ≈ 322 kmh

Another example is to convert meters per second to miles per hour, which has a conversion factor of 2.23693629. To illustrate this example, let's take Usain Bolt's record 100 meter run of 8.70 seconds. Dividing 100 meters by 8.70 seconds gives a speed of 11.5 m/s. The conversion to mph is then given by:

speed in mph = 11.5 m/s * 2.23693629 ≈ 25.7 mph

Below is a table of the conversion factors for typical speed unit conversions.

By default, the speed conversion calculator displays eleven of the most popular units of speed people use in their everyday lives. However, we also have seven other units of speed to explore. Here's how:

1. Enter your speed into one of the rows showing a commonly used unit, either in the imperial, metric, or other section of the speed converter.
2. In any one of the other rows, click on the unit and a drop-down menu will appear.
3. The converter then allows you to choose from the full list of units used in that category of speed units.
4. The speed converter will then display your speed in the unit you chose.
5. As a bonus, the speed converter also shows the pace of the speed in various units. Pace flips the speed formula around and states the speed in the amount of time per unit distance. We often use it to measure and compare running speeds in athletics.

We also recommend checking our dimensional analysis calculator.

To convert ft/s to m/s use the following equation:

speed in m/s = speed in ft/s * 0.3048

For example, a gazelle can reach a top speed of 70 ft/s. What's that in m/s?

speed of gazelle in m/s = 70 * 0.3048 ≈ 21 m/s

To perform the reverse conversion, m/s to ft/s, the equation is:

speed in ft/s = speed in m/s * 3.2808399

For example, a cheetah can reach speeds of 30.690 m/s. What's that in ft/s?

speed of cheetah in ft/s = 30.690 * 3.2808399 ≈ 100.69 ft/s

To convert m/s to mph use the equation:

speed in mph = speed in m/s * 2.23693629

For example, a skydiver's belly first terminal speed is 53 m/s. What's that in mph?

speed of skydiver in mph = 53 * 2.23693629 ≈ 120 mph

To perform the reverse conversion, mph to m/s, use the equation:

speed in m/s = speed in mph * 0.44704

For example, a Porsche 911 GT2 has a top speed of 204 mph. What's that in m/s?

top speed of Porsche in m/s = 204 * 0.44704 ≈ 91.2 m/s

To convert km/h to m/s use the following formula:

speed in m/s = speed in km/h * 0.27778

For example, a high-speed TVG train has a top speed of 320 km/h. What's that in m/s?

speed of TVG train in m/s = 320 * 0.27778 ≈ 88.9 m/s

To perform the reverse conversion, m/s to km/h, the formula to use is:

speed in km/h = speed in m/s * 3.6

For example, the speed of sound is 343 m/s. What's that in km/h?

speed of sound in km/h = 343 * 3.6 = 1,234.8 km/h

The equation to convert mph to ft/s is:

speed in ft/s = speed in mph * 1.46666667

For example, the maximum speed of an F-16 jet fighter plane is 1,500 mph. What's that in ft/s?

speed of F-16 jet in ft/s = 1500 * 1.46666667 = 2,200 ft/s

To perform the reverse conversion, ft/s to mph, use the equation:

speed in mph = speed in ft/s * 0.68181818

For example, a bolt of lightning can travel up to 320,000 ft/s. What's that in mph?

speed of lightning in mph = 320,000 * 0.68181818 ≈ 220,000 mph

If you live in the United States, the United Kingdom or their territories, you're in one of the only countries that still uses miles as the standard measure for speed and distance. Because most other countries in the world use kilometers instead, knowing how to convert from kilometers to miles – and then back again – comes in handy when you travel. It's also a vital skill if you work in a science field where the metric system predominates, or if you participate in footraces, cycling races or competitive rowing, all sports in which distances are usually given in kilometers.

To convert from kilometers into miles, multiply the distance in kilometers by 0.6214.

Any time you're asked to convert from one unit of length to another, all you have to do is multiply the first unit by the appropriate conversion factor. So, if you're being asked to convert km to miles, you'd do this multiplication:

\text{kilometers}\times\text{conversion factor}=\text{miles}

The conversion factor for converting kilometers to miles is 0.62137119, but for most purposes, being accurate to four decimal places is enough – so usually you'll use 0.6214 as your conversion factor. If you're not sure how many decimal places you must be accurate to, ask your teacher.

Tips

• You'll probably need to memorize conversion factors for tests and quizzes, and any conversions you do frequently in school or in real life are likely to stick in your head. But it's also very common to look up conversion factors in a reference book or your notes. Unless it's against the rules of a test, it's always better to double-check a conversion factor – and be certain you're correct – than to guess.

Imagine that you're being asked to convert 5 kilometers into miles. You already know how many kilometers you're being asked to convert, and you know the conversion factor; so all you have to do is fill them into the conversion formula:

5\text{ kilometers}\times 0.6214=? \text{ miles}

Once you do the multiplication, you'll have your answer:

5\text{ kilometers}\times 0.6214=3.107 \text{ miles}

If you've ever run or walked in a mid-distance race, this is probably a familiar number; 5k or 3.1 miles is a very popular race distance.

Tips

• In this case, the miles are rounded to one decimal point because most runners don't care about the extra 0.007 miles. Context is very important when you're deciding which decimal place to round to.

If you have reason to convert kilometers to miles, you'll probably need to do conversions in the other direction, too: going from miles to kilometers. The simplest way to do this is to perform the inverse of the operation you used to go from kilometers to miles. So if you multiplied by 0.6214 to convert from kilometers to miles, you'll divide by 0.6214 to convert from miles to kilometers.

Try it out with 3.107 miles, which from the previous problem you know is equal to 5 kilometers:

\frac{3.107\text{ miles}}{0.6214}=5\text{ kilometers}

There's just one problem here: How do you know if you should be dividing or multiplying by the conversion factor? You can double-check by remembering which unit is larger or smaller than the other. In this case miles are longer than kilometers, so if you convert from miles to kilometers, you should end up with a bigger number. If you go the other way, from kilometers to miles, you should end up with a smaller number.

Imagine that you're asked to convert 10 kilometers into miles, but you mistakenly divide by the conversion factor instead of multiplying. Then you'd have:

\frac{10\text{ kilometers}}{0.6214}=16.092693917\text{ miles}

But you know miles are longer than kilometers, so your result should be smaller than what you started with, not bigger. If you've double-checked your conversion factor and are sure you got it right, that means you should be multiplying instead. That gives you:

10\text{ kilometers}\times 0.6214 = 6.214\text{ miles}

This time your result (in miles) is a smaller number than the kilometers you started with, which means you chose the right operation for your conversion.