How many miles is a 5K, a 10K and a half marathon?

American road races mix units. The 5K, 10K and 15K are named in kilometers, while the half and full marathon are usually quoted in miles. The distances are the same everywhere. A Boston 10K and a Tokyo 10K are both 6.2 miles.

The K simply stands for kilometers, so a 5K is 5,000 meters and a 10K is 10,000. Races named in miles go the other way: a 5-mile race is about 8 km, and a 10-miler is about 16 km. When a race page lists both, the miles figure is usually rounded. Trust the kilometers if you need the exact number for a watch or a training plan.

One mile is 1.609 kilometers, and one kilometer is 0.621 miles. That gives two quick methods:

• Kilometers to miles: multiply by 0.621. A 10K is 10 × 0.621 = 6.21 miles.
• Miles to kilometers: multiply by 1.609. A 4-mile Turkey Trot is 4 × 1.609 = 6.4 km.
• In your head: kilometers × 6 ÷ 10 gets you close. 5 km × 6 ÷ 10 = 3 miles, a little under the real 3.1.
• Going the other way: miles × 1.6. A 3-mile loop is about 4.8 km.

Pace converts the same way. A 10-minute mile is a 6:13 kilometer, and a 6-minute kilometer is a 9:39 mile. The pace calculator does the arithmetic for you.

Every challenge counts each session the X Challenge app records inside its window, so none of these has to be covered in one go. The longer ones are built for a daily walk or run over a season. See all the challenges.

A number like 179 km looks impossible until you divide it by the days you have. Dragon is 179 km, about 111 miles, over 88 days. That is about 2 km a day, or a walk of under 30 minutes at 3 mph. Phoenix works out at about 1.8 km a day, a walk of under 25 minutes.

At the short end, Loki is 5 km over 7 days, under 10 minutes of walking a day. Thor covers almost exactly a half marathon at about 1.1 km a day. Few people go out every single day. Most do three to five longer sessions a week and take the rest off.

Typical beginner plans give you a rough timeline. Each step assumes you can already cover the one before it comfortably.

Covering a distance over several sessions takes far less preparation. A 10K split over a week is about 1.4 km a day, less than a mile, which most people can walk now. For a first plan, see your first virtual 5K.

A 5K is about 6,500 steps for most adults, more if you have a shorter stride. A standard outdoor track is 400 meters in the inside lane, so one lap is about a quarter of a mile. Four laps are a little short of a full mile.

For more detail see how long a 5K takes to run, how long it takes to walk a 5K or 10K and 10,000 steps in miles.

• Most treadmills can show miles or kilometers. Check the setting before you start, or a 5K will end at 5 miles.
• GPS watches and phone apps can read a little long or short, especially among tall buildings or under trees. A difference of 1 or 2 percent is normal.
• Track laps are the most accurate check. If your app says 1 mile after four laps in lane 1, it is reading slightly long.
• For a treadmill virtual run, check how your app records indoor distance before you rely on it.

If you are new, start with a 5K. It is long enough to feel like an achievement and short enough to reach in a couple of months. On X Challenge that is Loki: 5 km over 7 days. A 10K is the usual next step, then the half. If you are choosing between them, read which distance to choose.

• Choose a 5K if you are new to running, coming back after a long break, or want a goal you can reach in a couple of months.
• Choose a 10K if you already run 30 minutes comfortably and want something that takes a few more weeks of work.
• Choose a half marathon if you have run a 10K and have three months and three or four runs a week to give it.
• Choose a long multi-week distance if you prefer walking, want a daily habit more than a race, or like a goal that lasts a season.

• Is a 5K 3 miles? Close. It is 3.107 miles, so a 3-mile loop leaves you about 170 yards short.
• Is a half marathon exactly 13.1 miles? It is 21.0975 km, which is 13.109 miles. Medals and shirts round it to 13.1.
• How many kilometers is a mile? 1.609. A 1-mile walk is 1.6 km.
• How many miles is a 50K? About 31.1 miles. Anything longer than a marathon counts as an ultra.
• How long is a Turkey Trot? It varies by town. Many are 5K, some are 4 miles (6.4 km) or 10K, so check the event page before you train.