One of the first steps to taking on a 100km is to find a race that fits your needs. A website like ultra sign up allows you to sort races by location, date and distance so you can easily filter through each one and choose what’s best for your schedule and fitness level. Once you’ve narrowed down your choices, you’ll want to consider tricky terrain and weather conditions as well as how long it might take you to finish based on your previous experience with shorter ultra distances.

Another important factor to keep in mind when choosing a race is the altitude of the area. If you live at sea level, you might not want to choose a race that takes place in an area with much higher elevation as it may be challenging for your body to circulate oxygen efficiently and this can lead to fatigue and discomfort.

Many runners come to this article because they are wondering how many miles is 100km, but the answer to that really depends on where you are. Kilometers belong to the metric system of measurement and are commonly used across Europe, while miles belong to the imperial or US Customary unit of measurement and are primarily used in the United States and the UK.

The metric unit of measurement for distance is the kilometer (km), which is equal to 1000 meters. The name derives from the Greek words for thousand and measure, so a kilometer is equal to one thousand meters. The US Customary unit of measurement for distance is the mile, which is equal to 5,280 feet or 1.609344 kilometers.