How to convert km into miles

How to Convert Kilometers to Miles

Updated December 14, 2020

By Lisa Maloney

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.

TL;DR (Too Long; Didn't Read)

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

The Km to Miles Formula

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.

• 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.

An Example of Converting Kilometers to Miles

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.

• 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.

Converting Miles to Kilometers

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}

So it checks out.

Which Way Do I Go?

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.

How to Convert Kilometers to Miles and Miles to Kilometers

home » units » articles » how to convert kilometers to miles and miles to kilometers

By Nick Valentine| Last update: 07 August 2019

Today we're going to take a look at how to convert between kilometers and miles, and back again. We'll take you through some tips for how to manually calculate the figures in your head, plus we'll give you a converter so that you can check your answers. Let's begin.

The standard 'converter' approach applied to the common problem of turning, say, 144 kilometres into miles would require you to remember that one km equals 0.62137119 miles and being able to multiply that by 144 in your head. Well, good luck with that. Rain Man might be able to do it. I certainly can't.

What I can do is to remember that, more sensibly, five miles equals eight kilometres and to use a trick an uncle taught me on an early drive through France.

You take the kilometre number, 144, and halve it; 72. Then take a quarter of your half, 18, and just add the two together. 72 + 18 = 90. That's your answer in miles.

How to estimate miles to kilometers

What about going the other way, for the European traveller trying to convert those weird miles into nice neat kilometres? Well, the obvious way is to divide by five and then multiply by eight. 90 ÷ 5 = 18 x 8 = 144.

So, yes, of course it works but there's a problem; While dividing by five is easy enough (divide by ten and double it), multiplying by eight is trickier. One way to solve it is to reduce the principal number to something that appears in the eight times table then convert it back. So that 18 could be halved to nine and we all remember, don't we, that nine eights are 72. Double back again and we get to 144.

Advertisements

As an alternative, let's think about about a kilometre equalling (roughly) six tenths of a mile. This is why British and American soldiers stationed in Germany were taught an 'on manoeuvres' converter: divide the miles by six and move the decimal point one point to the right.

Let's try it. Six goes into 90 fifteen times. Express that as 15.0 and move the decimal point one place right and arrive at 150. You can also divide by three and multiply by five: 90 ÷ 3 = 30 x 5 = 150. Pretty close (but I hope they don't use it for calculating artillery ranges).

Again, though, there's a formula that's almost as easy to work out in your head but delivers a precise result. Divide the number of miles by five and subtract that from the original. Then double the resulting number. So:

Quick figures

1 km: 0.62137119 mi
1 mile: 1.609344 km

90 miles ÷ 5 = 18.
90 - 18 = 72.
72 x 2 = 144 kilometers.

That'll do nicely. Did you see what we did there? Turned the miles number into four fifths and then doubled it to make eight fifths, or the reverse of five eighths. Sometimes fractions are easier than decimals.

Of course, if you're looking for a pain-free method of doing the calculation right here and now then you can use our handy kilometers and miles converter, below.

Kilometers and miles converter

For future reference, the regular miles and kilometers conversion tool is here. You'll be happy to hear that this website provides a comprehensive list of online conversion tools. So, should you wish to convert between kilometers, miles and any other units of distance, give the length and distance converter a try.

Advertisement

Rate this article

Please rate this article below. If you have any feedback on it, please contact me.

report this ad

Unit features

1. Cm and Feet Conversion
2. Kilograms and Pounds Conversion
3. Watts to Amps Calculator
4. How Big is an Acre?
5. How Much Does a Gallon of Water Weigh?

The History of the Calculator

From abacus to iPhones, learn how calculators developed over time.

Convert kilometers to miles online converter

Kilometers to miles (km to miles) converter

Kilometers (km)

Copy

Miles

Copy

0123456789121518

1 kilometer is 0.62137119224 MILS

1 miles 1.609344 kilometers