kilometer

Imagine walking around your neighborhood—that's a distance often measured in meters. Now imagine going from one town to another. That's where a kilometer comes in. A kilometer is a unit of length equal to 1,000 meters, or about 0.62 miles. People use it for distances that are too long to talk about in meters, such as road trips, running races, or the space between cities.

The word comes from parts that mean "thousand" (kilo-) and "measure" (-meter). So it literally means "a thousand measures." You'll often see "km" as its abbreviation. If you're planning a hike, the trail map will likely show the distance in kilometers. Running a 5K race? That's 5 kilometers—a very common race distance around the world.

A kilometer (km) is a metric unit of length equal to one thousand meters. It is a common unit for measuring longer distances. While meters work well for the size of a room or the length of a pool, kilometers are more useful when talking about travel, geography, and other larger spaces.

Think about it this way: if you were driving across a country, you wouldn't say, "I drove 500,000 meters!" You would say, "I drove 500 kilometers." In the same way, the distance between cities or the length of a coastline is often given in kilometers. Maps and road signs use kilometer markers to show how far places are from each other, which helps travelers find their way.

Kilometers aren't just for land travel, either. They can also be used to talk about height or altitude, such as the height of a mountain, and even very large distances, such as the width of a planet. For much greater distances in space, scientists use other units.

The metric system, which includes the kilometer, is the official system of measurement in most countries. That makes this unit important when traveling internationally, reading scientific information, or understanding distances on maps. So the next time you see "km" on a sign, you'll know it marks a stretch of one thousand meters.